Turning off an engine / run away vehicles - PeachParts Mercedes-Benz Forum

davidmash · #1 08-28-2012, 10:12 AM

A few of us at work were talking about while watching the piece on the run away SUV. I asked why people do not know to shut the engine off.

I know that with car that have a button start that you need to hold the button down for an extended period of time to shut the engine down and that most people probably do not know that. A woman with a VW said that she cannot turn the key when the car is in Drive. Is that true? If so that seems very unsafe. I would think people would know to pull the car out of gear at the very least but I know people are generally ignorant about cars and their operation. What the heck do they teach in drivers ed about this situation?

Benz Fan · #2 08-28-2012, 10:18 AM

I've never encountered a vehicle that cannot be shifted from "Drive" to "Neutral" in virtually any circumstance. Many modern vehicles even have a rev-limiter to prevent engine overspeed if the accelerator is pressed while in "Neutral".

SwampYankee · #3 08-28-2012, 10:21 AM

Off? Neutral? Jam it into park? Always my first thought when I see these stories. I hadn't thought about the complications that could arise with lockouts/"safety" switches. Those are certainly viable options in my current (read older, cheap) fleet, maybe not so with newer cars?

MS Fowler · #4 08-28-2012, 10:39 AM

Don't forget the steering interlock. Turning the key too far past "off"locks the steering--not good in an emergency situation. By the way, this happened to a friend of mine 20 years ago. Husband was driving and has a heart attack, wife turned the kep to "off" , but went too far and locked the steering so she had no control. She couldn't get to the brakes and the steering wheel locked. Ended up hitting bridge supports, and broke both her knees. Husband survived OK.
Unintentional consequences are always ready to complicate the situation.

davidmash · #5 08-28-2012, 11:10 AM

The 124 has a lock out for the steering lock. If the car is not in park you cannot turn the key to the final part to lock the steering wheel and pull the key out.

I suspect in this latest run away car incident it was a combination of panic and not knowing that holding down the start/stop button would kill the engine. Does anyone have a start stop button that that they can verify if you hold it down it will shut off? I seem to remember reading that in one of those "what do do when" articles.

Txjake · #6 08-28-2012, 11:26 AM

most drivers are ignorant of emergency actions. Driver's Ed does not teach that.

G-Benz · #7 08-28-2012, 11:41 AM

It's easy to "armchair" quarterback" what appropriate scenario should occur in a runaway vehicle situation...it's very different to actually experience it!

Driving in heavy traffic, avoiding barriers, other vehicles, pedestrians, possible inclement weather condition, etc...many distractions that can inhibit clear thinking...

Hatterasguy · #8 08-28-2012, 12:14 PM

I had a couple run aways over the years caused by floor mats.

I don't know of one push button start car where you can shut it down by either holding it, or hitting it fast a few times. Also you can always take it out of gear.

Problem is most people don't know what the N stands for.

retmil46 · #9 08-28-2012, 12:21 PM

Not to mention the old adage "you have more horsepower in your brakes than your engine".

IMO, as it's already been stated in this thread, boils down to operator error - not knowing what to do in an emergency situation ahead of time, coupled with the panic of being caught in said situation.

Lack of drivers ed, owners never bothering to crack the owners manual, appliance drivers that just pour in gas and drive it until something breaks - take your pick.

But again, with all the electronic controls being added to virtually every system on a vehicle these days, it's not outside the realm of possibility that a software bug or electrical fault could defeat all the measures we've discussed and actually prevent someone from stopping the engine and/or vehicle.

Personal experience - I've got an 05 Jeep Liberty diesel, with an electronically controlled 545RFE transmission. For a few months I tried using one of the Scangauge II displays hooked up to the OBD port. After starting to use the display, I had several instances where driving along at speed - anywhere from 35 mph up to 70 mph on the interstate - there would be a loud WHAM that shook the whole vehicle, the transmission would drop completely out of gear into neutral, and the engine would go to idle regardless of the position of the accelerator pedal - after 2 or 3 seconds, the transmission would start reengaging itself, until it was back in the proper gear for whatever speed the vehicle was still traveling at, and the accelerator pedal (drive by wire potentiometer affair) would respond again.

I had my local tranny guru hook up his high-end scanner to the vehicle, and he found several hidden codes where the TCM had completely lost signal to the data bus, and rebooted itself at speed.

The culprit turned out to be the Scangauge display - it was putting out so much noise on the data bus that it was occasionally causing the TCM to lose signal. Once I disconnected the display and stuck it in the closet, there were no further instances of tranny misbehavior.

MS Fowler · #10 08-28-2012, 12:25 PM

^^^
If my memory isn't failing, I seem to remember that the standard design parameter was 3 times more power in the brakes than the engine. 3:1 One reason I discounted all those "runaway Audi" stories. The brakes always are more powerful than the engine.

tbomachines · #11 08-28-2012, 12:28 PM

I think Ferrari should look into that woman for their F1 team to replace Massa...

Txjake · #12 08-28-2012, 12:38 PM

And, there's always sideswiping the armco barrier to slow yourself down, if all else fails.

Truly though, it's automotive darwinism

retmil46 · #13 08-28-2012, 12:40 PM

Quote:

Originally Posted by tbomachines

I think Ferrari should look into that woman for their F1 team to replace Massa...

Agreed. If nothing else, she displayed vehicle control and driving ability far above the average driver - enough sangfroid on her part, it makes me wonder if she didn't actually try some of the methods we've discussed here - and for whatever reason they didn't work - ie, electronic TCM fault overrode the gear selector position and kept the tranny in gear, electronic ECM or traction control overrode the electronic ABS brakes, etc.

spdrun · #14 08-28-2012, 12:41 PM

Instead of a button talking to a computer, why not require a physical OFF/ACC/RUN/START dial on keyless cars? Moving the switch to OFF would positively cut power to the injectors. Steering lock would only be engaged if the car is completely stopped.

A kill switch like on motorcycles would also work fine. The US has plenty of safety rules. Something like this is a no-brainer.

Txjake · #15 08-28-2012, 12:42 PM

Quote:

Originally Posted by retmil46

Agreed. If nothing else, she displayed vehicle control and driving ability far above the average driver - enough sangfroid on her part, it makes me wonder if she didn't actually try some of the methods we've discussed here - and for whatever reason they didn't work - ie, electronic TCM fault overrode the gear selector position and kept the tranny in gear, electronic ECM or traction control overrode the electronic ABS brakes, etc.

and that's why we insist in aircraft to have redundant failsafes on critical systems......