The ignition switch? 7

[enginesrus]

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.

 

[3DDave]

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.

 

[enginesrus]

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.

 

[BrianPetersen]

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.

 

[IRstuff]

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)
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[enginesrus]

Turn off the ignition switch you say?

https://www.bestattorney.com/blog/a...den-unintended-acceleration-08-toyota-tundra/

 

[3DDave]

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.

 

[enginesrus]

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?

 

[LionelHutz]

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.

 

[enginesrus]

I guess that last comment explains it all.

 

[3DDave]

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

 

[IRstuff]

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)
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[gruntguru]

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 . . . .

je suis charlie

 

[Lou Scannon]

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

 

[SwinnyGG]

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.

 

[BrianPetersen]

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.

 

[GregLocock]

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


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[JayMaechtlen]

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

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[BrianPetersen]

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.

 

[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.

 

[gruntguru]

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