Handling brake failure/stuck accelerator in auto transmission cars

  • #1
Wrichik Basu
Insights Author
Gold Member
2022 Award
2,026
2,177
It's been a year since I was issued my driving licence. I have never driven automatic transmission cars, so my idea about them is very faint. I know that there is no clutch pedal, and one doesn't have to shift gears while driving forward - that's it.

Last day, I was watching a TV show where they showed the case of a car in which the accelerator pedal was stuck. The terrified driver had called 911, and cops assisted her in bringing the vehicle to a stop.

I was thinking what I should be doing in case I am in a similar situation - break failure or a stuck accelerator pedal. First, it is important to navigate properly so that I do not hit a lamp post, another car or a pedestrian. In my city, the maximum allowed speed is 60 km/h, but it is rarely possible to drive above 40 km/h in the traffic. So consider that I am on a highway where I am driving at around 80 km/h - 100 km/h (or maybe more).

I have an idea on how to handle the situation in manual transmission cars - press clutch and shift the gear to neutral. Once the engine is disengaged from the wheels, the speed will gradually decrease, and below a certain speed, I can engage the hand brake (or parking brake, whatever you call it) slowly. The car will have a chance of skidding, but nothing can be done about that. Another option is to shut down the engine. However, I would lose the power steering. In our car, power steering automatically switches off at speeds > 60 km/h. But in case of a break failure/stuck accelerator, I would like to take advantage of power steering whenever it is available, so switching off the engine is not a viable option.

What about automatic transmission cars? If the accelerator is stuck or the car is speeding at 100 km/h, can I forcibly change the gear from drive to neutral? If the car has a push-button for ignition rather than a key, will I be able to shut down the engine suddenly? I don't want to do that even if it is possible, for reasons mentioned above. Would it be safe to engage the hand brake at high speeds? What is the best way to stop the car in this situation?

I found a few questions on Quora regarding this, but I don't consider it to be a credible site.
 

Answers and Replies

  • #2
256bits
Gold Member
3,765
1,793
Put the transmission in a lower gear.

Honestly, whenever this would happen, one would be so flabbergasted that the mind would freeze up in panic.
Even if I would know what to do, I wouldn't know what to do, if coming upon an intersection with a red light, or traffic is heavy with a vehicle in front of me.
One would have to practice on a course to possibly have an "innate" response, such as is given for airline pilots in situation training. .

Shutting off the engine immediately - that also befuddles the brain as it is out of the ordinary when driving a car. Wait for panic mode to subside.
Some cars might might lock up the steering automatically ( who knows what type of safety feature designers put in these things these day - solve one problem, create another )- you would have to check. Maybe most don't. You certainly would not want to turn the key too far and definitely lock up the steering.

Taking it out of gear - coasting would need a long, long distance for the car to reduce speed.
I would say put in lower gear, and when out of panic mode, then shut the engine off for engine breaking.

Another option, if possible is to slide the car into the side rails for deceleration, as long as you don't flip on uneven pavement, or a gravel shoulder. the side of the car will look like crap afterwards.

Power steering - isn't much of a concern - one doesn't need power steering when in motion, its use comes mainly for slow speeds, such as for parking.
Power brakes - you need that, as the effect is evident, without much more pressure is required on the pedal, but if you loose brakes that doesn't really matter,
Hand brake - if you press too much, you could lock up the rear wheels, so one would want to handle the release as well as applying pressure to the pedal.
 
  • Like
Likes Astronuc and Wrichik Basu
  • #3
14,194
8,183
For a manual shift on brake failure you have two options:
1) hand brake
2) downshift and let the engine slow you down

For an automatic, there are choices like 1, 2 D N R where 1 and 2 are slower speeds so you could shift to them but I've never tried that. I 've heard of someone shifting into reverse while driving forward at some fair speed and then destroying the transmission.



This guy shows downshifting to get a speed jump but it looks like you could use it to slow down too.

http://knowhow.napaonline.com/downshift-automatic-transmission/

https://www.apautoparts.com/things-never-automatic-transmission/

Anyway, it's not something you should ever do just to try it out.



 
  • Like
Likes Wrichik Basu
  • #4
BillTre
Science Advisor
Gold Member
2022 Award
2,216
7,353
Try shifting to neutral.
Try shifting into some other gear if neutral does not work.
Try engaging hand brake gradually, if possible.

Experimenting with your car before a failure should determine what you can do, like turning off the engine. You might be able to retain power steering, or some you might be able to still steer without the power.
You might be able to turn off the engine, but keep other systems going possibly including the power steering.

Depending upon your situation, more drastic actions may be appropriate.
 
  • Like
Likes Wrichik Basu
  • #5
256bits
Gold Member
3,765
1,793
Experimenting with your car before a failure should determine what you can do, like turning off the engine. You might be able to retain power steering, or some you might be able to still steer without the power.
Probably an idea. But not for everybody to try out.
As long as one does not screw up and cause an accident while testing.
Explain that to the police when they come asking what happened.
That's why I stated to do it under supervision, and controlled circumstances.

Road conditions and weather play a part here - slick or icy conditions in winter, rainy weather, a dry road. Day time or night time.

Try turning the wheels when stopped and no engine - very difficult.
Under motion, as I already said, turning the wheels requires little effort, as well as a very mild turn on the steering wheel sets the car on a different course. Power steering not needed while in motion.
 
  • Like
Likes Wrichik Basu
  • #6
berkeman
Mentor
64,179
15,398
I was thinking what I should be doing in case I am in a similar situation - break failure or a stuck accelerator pedal.
Stuck accelerator pedal -- shift into neutral and leave the engine on long enough to brake and stop by the side of the road. Shutting off the engine eliminates the power brakes and steering, which is a bad thing (do not ask me how I know this first hand). Probably you should use your blinker when braking to the side of the road, as that is more helpful for the cars behind you versus using your 4-way flashers while pulling over. Switch to 4-way flashers as you shut off the revving engine after you have stopped on the side of the road (hopefully in a relatively safe place). Usually it is best to stay in your car while you call for help on your cellphone.

A brake failure is different. As others have said, you can shift down to lower gears to help slow you down, and try using your emergency brake since it uses a completely different braking mechanism. Use your blinker and then flashers similarly to above.

BTW, shifting from Drive into Neutral in many cars is quite easy, with that direction of shift not requiring a button push to enable the change (versus shifting from Drive down to 2nd, for example). It's good to practice doing that simple bump of the shift lever from Drive to Neutral a few times to be sure you know how to do it.

The video posted that says never shift from Drive to Neutral is about normal driving, not an emergency response to an over-revving engine. Stay safe!
 
  • Like
Likes BillTre, sysprog, Lnewqban and 2 others
  • #7
sysprog
2,613
1,783
Sudden complete failure of primary brakes is extremely unlikely; suddenly stuck accelerator is extremely unlikely; both conditions at once is extremely extremely extremely unlikely.

For the brake failure, you may be able to use engine braking even with an automatic transmission; however, some newer cars may inhibit this possibility, and even in older cars it's not as effective as it is with manual transmissions.

The auxiliary (emergency/parking) brake, usually cable-actuated, is not functionally dependent on the hydraulic operation of the primary braking system, so you can use it, albeit less efficaciously, when the primary brakes are not operational.

What effectiveness the auxiliary brakes or primary brakes have will be greatly reduced if they have to fight against the effects of a stuck accelerator, so in such an eventuality, you should stop the engine, preferably while shifting to 'low' ##-## with a pushbutton ignition you can hold the button down for a few seconds to accomplish that.

Depending on the details of the situation, you may be able to stop by going off the road, or turning uphill, or putting the car into a spin, if you can manage that.
 
  • Like
Likes Wrichik Basu
  • #8
Lnewqban
Homework Helper
Gold Member
2,641
1,431
It's been a year since I was issued my driving licence. I have never driven automatic transmission cars, so my idea about them is very faint. I know that there is no clutch pedal, and one doesn't have to shift gears while driving forward - that's it.
...
What about automatic transmission cars? If the accelerator is stuck or the car is speeding at 100 km/h, can I forcibly change the gear from drive to neutral? If the car has a push-button for ignition rather than a key, will I be able to shut down the engine suddenly? I don't want to do that even if it is possible, for reasons mentioned above. Would it be safe to engage the hand brake at high speeds? What is the best way to stop the car in this situation?

Don't worry much, modern cars are very safe, and is very unlikely that you will suffer any of those failures for hundreds of thousands of driven kilometers.

Basically, both types of transmissions are pretty much the same regarding internal gears and transferring of power from engine to wheels, the difference is in the clutch and torque converter.
The clutch gives the driver the ability of isolating torque between engine and gearbox at will.

The converter way of work is rpm-dependent and remains engaged all the time. There is very little transferring of torque while the engine is at idle, but as soon as rpm's are increased, the converter becomes almost a solid connection between engine and gearbox.

Please, see:
https://en.wikipedia.org/wiki/Torque_converter

Most shifters for automatic gearboxes give the driver the ability to easily switch from D (direct) or R (reverse) to N (neutral) anytime the ignition key is in and turned to On position.

All engines have a revolution's limiter that prevents a running wild engine from destroying itself due to a full open gas-no load condition. Hence, never hesitate switching to N in an emergency.

Shutting the engine off while the car is still moving is a last resort and should be avoided because while the engine is turning, it helps multiplying the braking and steering force of the driver, among other things.

All modern cars have two brake systems in one, left front tire is stopped by same hydraulic circuit than right rear tire, even in the rare event that the circuit actuating on right front and left rear tires lose pressure or fully fails (or vice-verse). You can only lose 50% of braking capability at once.

Fully engaging the emergency brake at high speeds is very dangerous because, if the driver locks the rear tires (only ones having that type of brake), the car will fishtail from side to side while slowing down. If it needs to be used at all, gradual or partial application would be more controllable.

It is very important to keep the battery of a car with automatic transmission fully charged and in good condition. Due to the torque converter, it is impossible to bump starting an engine by pushing the car or using a hill. Always keep some jumper cables or package in your car, just in case.

To make things more difficult, many modern cars have electric assisted steering: suddenly failure of battery means difficult or impossible steering at any speed.
Some even have fly-by-wire control systems, which fully depend on availability of electric power.

Back when brakes were not so good, a way to reduce speed and stop a car was rubbing the sides of the tires against a curbside, if available.

Also, keep the pads of your brakes from becoming too thin, keep sliding pins from working without lubrication and becoming worn, and replace the brake fluid every year if you can, especially if the car is frequently in humid weather conditions. That fluid absorbs humidity over time, which could become steam inside the hydraulic system of the brakes, reducing performance and corroding internal parts.

There is more latent danger in neglected tires and wheels, which are the cause of many accidents.
Always keep the tires of your car in proper condition and check the pressure as frequently as you can, especially immediately before a long trip in summer time. Low pressure and heat are a combination to avoid.
Check that all nuts of the wheels are torqued down evenly (otherwise brake disks can get deformed) and properly.

Keep calm and drive on! :cool:
 
Last edited:
  • Like
Likes Astronuc, Wrichik Basu and sysprog
  • #9
jrmichler
Mentor
1,977
2,523
I have had to deal with a throttle sticking open on two different vehicles. In a 1955 Ford truck, carburetor ice stuck the throttle open going up hill. I was able to kick the linkage and break the throttle free. In a Chrysler K car, carburetor gunk caused the throttle to stick open. I stepped hard on the brakes, stopped the car, shut off the engine, then sprayed carburetor cleaner into the carburetor until the throttle freed up.

I once, as a test, tried stopping a car using only the parking brake. I slowly applied the brake. Nothing, nothing, then the car spun out before I could catch it. The parking brake only brakes the rear wheels, but it will stop the car.

I have had several cases of total or partial brake failure. I came over a hill in a fully loaded 1961 Rambler at 80 MPH, then stood on the brakes to try to make the stop sign at the bottom. Those older cars were subject to brake fade, and the brakes went out completely at about 25 MPH. I put two wheel in the ditch and whipped around the corner, running the stop sign. The road ended in a T-intersection.

In another case, I had just bought an early 1960's Austin Healy Sprite for $200, which gives an idea of the shape it was in. It ran fine in the test drive. On the way home, the brakes failed completely on a downhill stop. The parking brake did not work at all. So I downshifted, slowed down, put two wheels in the ditch, ran the stop sign, and made it around the corner.

I had a brake fail in a 1947 Beech Bonanza. Airplanes have separate brakes for the right and left wheels. That was a simple matter of steer right and brake left, and use a little more runway than originally expected. If that failed, I would have gone off the end of the runway, through a fence, into a pig farm. Messy and expensive, but not dangerous.

At one time, no cars had power brakes. People just learned to step hard on the brake pedal. When the power brake booster fails, the pedal gets hard, but the brakes still work. You just have to stand hard on the pedal with all of your strength. I drove a car that way for several weeks once, then fixed the brake booster.

At one time, no cars had power steering. Power steering is power assist. The steering wheel is always connected to the front wheels, and you can still steer if the power assist fails. It might take both hands on the steering wheel and all your strength, but you can always steer.

Everything you see on TV about brake failure and throttle sticking is wrong. You always have options. Downshift, shift into neutral, use the parking brake. shut the engine off, grab the steering wheel with both hands and steer, stand on the brake pedal as hard as you can, aim for something soft. Good drivers think about what can go wrong so they know what to do when something happens.
 
  • Like
Likes Wrichik Basu, BillTre and Astronuc
  • #10
berkeman
Mentor
64,179
15,398
I have had to deal with a throttle sticking open on two different vehicles. In a 1955 Ford truck, carburetor ice stuck the throttle open going up hill. I was able to kick the linkage and break the throttle free. In a Chrysler K car, carburetor gunk caused the throttle to stick open. I stepped hard on the brakes, stopped the car, shut off the engine, then sprayed carburetor cleaner into the carburetor until the throttle freed up.
What's a "carburetor"? :wink:
I have had several cases of total or partial brake failure. I came over a hill in a fully loaded 1961 Rambler at 80 MPH, then stood on the brakes to try to make the stop sign at the bottom. Those older cars were subject to brake fade, and the brakes went out completely at about 25 MPH. I put two wheel in the ditch and whipped around the corner, running the stop sign. The road ended in a T-intersection.
I think I saw one of the movies that you were a stunt driver in...

https://www.pontiactransamforum.com/data/seo_thread_images/PckIDpQ8fe.jpg

1594255145630.png
 
  • Haha
  • Like
Likes Wrichik Basu, BillTre and Astronuc
  • #11
Astronuc
Staff Emeritus
Science Advisor
20,995
5,052
First, it is important to navigate properly so that I do not hit a lamp post, another car or a pedestrian.
I once had a complete brake failure (in a 1983 Honda Prelude with manual transmission) while about to do a left turn on a divided highway. I was slowing to a left turn when the brake pedal went soft and hit the floor. I was doing about 50 mph (80 km/h) and I had to slow to about 15-20 mph (24 - 32 km/h), and cross oncoming traffic. I quickly downshifted to slow the car, and kept watch for traffic, while picking places I could run off the road into bushes if necessary. When I slowed enough, I applied the hand brake, which also failed (it wasn't independent). I went into the left turn, and fortunately, there was no oncoming traffic. Once clear of the intersection, I pulled off to the side of the road with the car in the lowest gear and turned off the engine to stop. I removed the rear wheel, which is when I discovered that a seal on the piston that pushes the brake shoe against the wheel hub and failed, thus I had no pressure in the brake system. The front and rear brake systems used common hydraulics, so it was a complete hydraulic failure. Also, the hand brake used the same brake shoes, but when the piston failed, it was loose and application of the hand brake pulled the brake shoe away from the piston, so the hand brake was disabled (the hand brake cable went slack, so I had no brakes). I was still two miles (3.3 km) from home, so I carefully drove home slowly and fortunately I had no further stops (stop signs or lights). One can prepare mentally for such emergencies by thinking through contingencies in such events, and being situationally aware in such emergencies. Downshifting can be done with some cars with automatic transmission.

I've also been in traffic when I lost control of a car when encountering ice on a highway. I had to drive of the highway onto the side, and one case, the car spun 180°, and I had to steer looking over my shoulder as the car traveled backwards along the shoulder.

I think I only once had a sticking throttle, but I simply turned the engine off with the gears in neutral.
 
  • Like
Likes jrmichler and Wrichik Basu
  • #12
Wrichik Basu
Insights Author
Gold Member
2022 Award
2,026
2,177
Thanks everyone for the input; I will try to follow your advice if I ever find myself in that unfortunate situation.
Also, keep the pads of your brakes from becoming too thin, keep sliding pins from working without lubrication and becoming worn, and replace the brake fluid every year if you can, especially if the car is frequently in humid weather conditions. That fluid absorbs humidity over time, which could become steam inside the hydraulic system of the brakes, reducing performance and corroding internal parts.

There is more latent danger in neglected tires and wheels, which are the cause of many accidents.
Always keep the tires of your car in proper condition and check the pressure as frequently as you can, especially immediately before a long trip in summer time. Low pressure and heat are a combination to avoid.
Check that all nuts of the wheels are torqued down evenly (otherwise brake disks can get deformed) and properly.
We take our personal car (a Toyota Etios Liva) for service annually at an authorised service centre, and, if I remember correctly, the brake pads have been changed once. Till now, I have only driven my car, except during the days of training. However, it does not mean that I will never drive someone else's car, and there is no guarantee that that car will be in good condition. At least in my country, a large percentage of cars are never regularly serviced. I have seen lots of cars which have absolutely plain tires, without any ridges. I have been a passenger in a car with slightly faulty brakes, and was seating in the front seat when it hit another car that was straight out of the showroom. I won't drive such a car if I know about its condition beforehand. Regular servicing for cars is very important.
 
  • #13
256bits
Gold Member
3,765
1,793
Thanks everyone for the input; I will try to follow your advice if I ever find myself in that unfortunate situation.
One thing to look out for,besides having a mechanical failure of car systems, is the a fault within the driving compartment ie things that can go under the pedals or around them
Such as:
The carpet flipping under the pedals
loose pop bottles, or other object, going underneath the pedal
A wandering dog or cat or pet trying to go and investigate that area around the pedals.

So try to keep the driver's area free from such objects.

A situation resulting in loss of brakes from the above can be just as traumatic as a mechanical failure.
For a manual transmission, this can also affect the clutch pedal with the inability to press , and failure to shift, ( unless you know how to power shift ) can also be as mind numbing.
 
  • Like
Likes Lnewqban and Wrichik Basu
  • #14
OCR
953
876
. . . was straight out of the showroom.


Lol. . . I think was is really the key word there. . :-p . :wink:

.
 

Suggested for: Handling brake failure/stuck accelerator in auto transmission cars

Replies
40
Views
857
  • Last Post
Replies
3
Views
839
  • Last Post
3
Replies
73
Views
3K
Replies
3
Views
528
  • Last Post
Replies
2
Views
301
Replies
1
Views
720
Replies
11
Views
688
  • Last Post
Replies
11
Views
397
Replies
28
Views
3K
Top