TrainTrac
Well-Known Member
More evidence that this is being way over-hyped by the media and ambulance-chasing trial attorneys.
2004 Toyota Prius: Three Ways to Deal With a Stuck Throttle
By Dan Edmunds | March 12, 2010
A recent report out of San Diego portrayed a runaway 2008 Toyota Prius careening out of control for miles at high speed on the open freeway in what was described as yet another case of unintended acceleration.
According to the driver, the throttle stuck open (not because of a rubber mat like shown above, he says) when he pulled out to pass a semi. Despite his best efforts, the brakes could not restrain the runaway machine. Additionally, he was quoted as saying he didn't want to put the car in neutral out of fear that this would "flip the car".
Well, we just happen to own a Toyota Prius of the same generation. Same color, too! So we set up a little test and invited John and Evan, members of our crack video production squad, to ride along.
The plan was simple. We would hold the throttle wide open and see if we could overcome the raging engine (and electric motor) by simply applying the brakes. After that, we'd try slipping the shifter into neutral before applying the brakes. And because some people have expressed concerns that a panicky shift towards neutral might wind up in reverse instead, we would shift into reverse on purpose to see what would happen -- at speed with the throttle floored, just like the preceding cases.
Place your bets. And don't let the fact that I'm writing this fool you. I could be dictating this from a hospital bed. Then again, I could be sitting at my cubicle with my feet firmly planted on a set of "slightly used, good condition" Toyota Prius rubber winter floor mats that I bought a couple of months ago from some recall profiteer on eBay.
<object id="flashObj" width="486" height="412" classid="clsid27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,47,0"><param name="movie" value="http://c.brightcove.com/services/viewer/federated_f9/1898242908?isVid=1&publisherID=1898241405" /><param name="bgcolor" value="#FFFFFF" /><param name="flashVars" value="videoId=71487982001&playerID=1898242908&domain=embed&" /><param name="base" value="http://admin.brightcove.com" /><param name="seamlesstabbing" value="false" /><param name="allowFullScreen" value="true" /><param name="swLiveConnect" value="true" /><param name="allowScriptAccess" value="always" /><embed src="http://c.brightcove.com/services/viewer/federated_f9/1898242908?isVid=1&publisherID=1898241405" bgcolor="#FFFFFF" flashVars="videoId=71487982001&playerID=1898242908&domain=embed&" base="http://admin.brightcove.com" name="flashObj" width="486" height="412" seamlesstabbing="false" type="application/x-shockwave-flash" allowFullScreen="true" swLiveConnect="true" allowScriptAccess="always" pluginspage="http://www.macromedia.com/shockwave/download/index.cgi?P1_Prod_Version=ShockwaveFlash"></embed></object>
Yawn. This was not difficult. We were able to defuse the situation with all three methods. Here are a few additional details ...
Brake test: Turns out there's a brake override feature in a Prius. As soon as I press on the brakes with anything more than casual effort, the wide-open engine and electric motors stop propelling the car forward and the brakes take over. Brake pedal effort is by no means what I would consider high. In a panic, with adrenaline pumping, this would be easy. Without adrenaline, it's still easy. What's more, it's not even startling because the gas engine goes to idle instead of revving to redline as a non-hybrid car would.
This system is necessary in a hybrid because, in simplified terms, the motor/generator at the heart of the system cannot simultaneously drive the car forward and supply regenerative braking force. It has to choose one, and the default is to choose brakes.
It is worth noting that the drivetrain WILL resume driving the car forward if pedal pressure is relaxed. You could string this along for miles if you were so inclined. But if you really want and need to stop this Prius with a stuck throttle using the brakes alone, you can in a matter of seconds without having to "stand on the brakes" in desperation.
At the end of all this, our Prius' brakes were just fine. No roasting, no fade, no smell. I drove it home and took the kids to dinner. I even demonstrated the above-described procedure for them on the way there.
Neutral test: People say a Prius is hard to put in neutral, but that's just wrong. Sure, the shifter is different from other cars, but with respect to neutral, the design is arguably better because you barely even have to take your hand off the steering wheel to pull the lever toward you. With respect to the non-standard nature of it, anyone who owned the car would learn it quickly. Besides, the shifter itself is clearly diagrammed and gated, so it's hard to screw it up.
You do have to hold the shifter in the "N" position for half a beat, though. The half-beat is necessary because the system is programmed to ignore accidental bumps against the lever.
Once in neutral, the car continues to coast at whatever speed you were at and it will respond to the brakes in a perfectly normal fashion. This is precisely why we recommend shifting to neutral as your first line of defense against a stuck throttle.
Reverse test: Like many newer cars, the Prius' transmission is electronically controlled. Therefore, it knows how fast you are going. It knows better than to give you reverse if you accidentally shift into that gear while moving forward at speed.
We shifted into reverse on purpose, with the throttle stuck wide open, and all we got was neutral, just like the previous case. Oh, and the car beeped at us to make sure we knew we screwed up. From this point, the brakes respond just as they did in the neutral test -- entirely normal.
Not all transmissions are set up to ignore a request for reverse while moving forward, especially older cars, but the Prius' certainly is.
