Here's an interesting question I have. And I don't really have any place here in Chicago to test this. Let's say your Prius for some odd reason, was accelerating out of control. Or engine was acting very oddly. Also assume there is no way you could pull to the side and address the issue, you just know you need to stop the car. If you stop the car, I assume by holding the Power button, would you: 1. have steering control (I assume no) 2. be able to still brake Secondly, let's say you were at highway speeds, and you were forced to do this. So you shut down your car. Could you start up the car again while the car was in motion, and again regain control of the car? At least with my '99 Civic, manual transmission, I could do all the above. Wonder if that is possible these days esp. with these modern cars. This discussion came up with my coworker when we talked about what we would do if our car accelerated beyond our control. I'm mainly wondering however what happens when you power the car off while driving.
Put the car in neutral (hold the shifter in position 2-3 seconds to engage since the it ignores "bumps" of ~1 sec). You will have full braking authority and power steering. Get it over to the side and then turn it off. This also worked in the '70's when sticky pedals were an issue that all teen drivers learned about. My husband experienced a runaway in a Volvo right after he started driving.
This has been addressed in previous threads. The posters have gone into the neutral position at speeds up to 80mph without incident.
You may lose electric steering if the car drops into ACC mode, however the brake booster continues to operate as long as it has power (and for a few pumps after that due to a capacitor backup in the event the 12V system dies).
From other posts I understand you will lose the power for the steering (much like a "conventional" car with the engine off) but will still be able to steer, although it will be heavy. The brakes should work normally for a few stops - after the vacuum is used up, they will still work but require a lot of effort. So if you get into a situation and simply hold down the power button, after 3 seconds it will shut off all systems and you should be able to steer to the side of the road while braking. If you have time to think, put it in neutral by holding the shifter to the right for a couple of seconds, then steer and brake (as noted above, both should still be fully powered). Both have been tested by intrepid board members.
Just to be entirely accurate, it's not "vacuum" you run out of it's hydraulic pressure. That's what you hear when you first start up the car by pressing the brake pedal. The pump filling the hydraulic accumulator. Prius brake booster doesn't run on vacuum. Go ahead and try it. The steering gets a little heavier, but not problematically. Even if the brakes run out of hydraulic pressure they also are still fully usable. This IS, after all, a small car (3000 ish lbs).
My thread on it got locked but it should be as simple as applying the brakes and the engine should cut out, right? If is still accelerating that means the brake override has failed. You should be able to apply and remove the brake to control your speed in theory to get to the side of the road. http://priuschat.com/forums/gen-iii-2010-prius-main-forum/75773-brake-override-system.html
These posts are ALL very good (with a couple of errors and omissions), however, this discussion is relatively academic since the easiest, fastest and safest way to disable a runnaway engine (iregardless of its cause( is to simply put the car in Neutral, by pulling the gearshift to the LEFT, holding it there for approximately one (1) second, and ALL will be well! The engine will go to idle, and the steering and brakes will be FULLY operational. There will be NO agonizingly long 3 second wait for the engine to shut off and you'll NOT be fighting sluggish steering, or pushing extra hard on the brakes. You'll simply be able to steer your car NORMALLY to the side of the road and call for help. This all works as advertised...I know because we've done it twice at city and highway speeds, there's NO drama whatsoever! Like the old commercial used to say, "try it, you'll like it"! David (aka Blind Guy)
Thanks guys, these posts seem to clear it up. So for those regular Toyota cars (Camry, etc.) that had unintended acceleration problems, why didn't the owners just switch to neutral or even turn off the engine? Just didn't think about it? I switch to neutral all the time since its a habit/holdover from my stick-shift car, so this would be easy for me. I've even turned off the engine in the same car while moving at 30mph and started it up again as well (had an aftermarked cold-air intake on that car that is naturally about a foot off the ground, so I was trying to avoid a big puddle so that my engine wouldn't suck water/hydrolock).
Either ignorance of how cars work or they are older individuals who still fear blowing up an engine by throwing it in neutral? Some people don't realize that modern cars have rev limiters built in so blowing an engine is not much of a problem anymore. There could be mechanical reasons why putting the gear selector in neutral would not stop the car from accelerating but I'm not versed well enough on the throttle mechanisms on the other cars.
Try both of these with the car turned off and parked, and the fob at the other end of the house. I can still turn the steering wheel. It is stiff, but not as bad as on heavier cars when the power assist is not assisting. The brake booster fires up the moment the door is opened, before even stepping in, so it doesn't require the ignition to be turned on. The 1 second wait is not necessary. Try shifting to Reverse. It overrules and goes to Neutral instantly. At least my 2010 does.
At any speed about 15mph, shift in to R. Because the shifter is electronically controlled, it'll realise you're trying something stupid and will shift into N. It's just another alternative to holding it in N for a split second. Pressing Park also shifts it into Neutral at speeds. Disclaimer: I say 15mph as a safe bet. The actual limit is lower but I didn't want people try out and then coming back saying I've busted their car.
All previous posts on why shifting to neutral is the best answer. BUT...if you do turn off the car I'm pretty sure (I haven't tested this) you will not be able to restart it while in motion. In order to start the Prius there are several interlock conditions that must be met, such as being in Park and having your foot on the brake. If the car is moving, you won't be in park, but rather neutral, even if you pushed the park button. So, if you do press the power button for the required 3 seconds and do shut off the car you will lose power steering, but still have heavy mechanical steering and you will have friction brakes with some power assist for some time before you fall back to non-power assist friction brakes. 3PriusMike
