OK, this has nothing really to do with marketing, but it's relevant to my last post about the damage to Toyota's brand that will be caused by all its recent recalls.
This time, MSNBC reports that on top of the massive gas-pedal recall which was on top of the massive floormat recall, which was on top of the rusting-truck recall, Toyota is recalling 270,000 of its Prius model due to "allegations of momentary loss of braking capability while traveling over uneven road surfaces, potholes or bumps."
I'm here to tell you, this is VERY common among cars with Anti-Lock Brake systems (ABS) and unless the Prius is really, really bad for it, I submit that it's unfair to single out Toyota. I've had it happen to me in several cars with ABS, across a wide variety of manufacturers, and I guarantee the problem people are experiencing is due to what's called "Ice Mode" in the ABS calibration.
You see, ABS works by monitoring the speed of each wheel on the car, and when it detects that any of them is decelerating much faster than the rest, it interprets that as the wheel being in a skid, and momentarily releases the brakes on those wheels. Skidding tires don't slow the car as well as rolling tires do, and they don't provide any steering capability at all, and ABS is there to ensure that the tires stay rolling. That's its job.
But there's a darker side to this: The ABS system doesn't just compare the speeds of the wheels to each other. The ABS is programmed to know what rate of wheel deceleration is even possible under the highest-deceleration conditions possible for the car. If the deceleration of all the wheels exceeds the rate the ABS thinks is possible, then it assumes the car is on a very slippery surface, and that all the tires are locking up. So what does it do? It pretty much takes your brakes away for a second or two. On ice, this is not a bad thing. It'll make sure you have whatever traction ice will afford so you can still kinda steer the car.
But there's something else that can trigger the same kind of wheel deceleration, and put the ABS into Ice Mode: Going over a bumpy surface while braking...such as approaching a stoplight on a poorly maintained city street. Every time a wheel hits a bump, it very briefly bounces up and loses traction, and if the brakes are applied at the time, the wheel will decelerate briefly and quickly. Behold, the ABS thinks it's on a slippery surface, and pretty much takes the brakes away from every wheel exhibiting the same behavior. If all of the wheels are doing it, it takes the brakes away from ALL of the wheels. You could Fred Flintstone the pedal right through the floor of the car, but the ABS thinks it's smarter than you are, and you're not asking nicely, so...NO BRAKES FOR YOU!
At a minimum, this is maddening to experience when you're by yourself on the road or track. It's downright frightening, and frankly dangerous, to experience it when you're faced with a stopped car 15 feet in front of you and you're still going 20 mph, with no brakes.
I hope this issue is found to not be unique to the Prius or to Toyota, so that it exposes the issue as the practically industry-wide problem that it is.
Ice Mode. Mark my words. You heard it here first.
Thursday, February 4, 2010
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4 comments:
So, what you are saying is that the Toyota CEO who has been seen sweating on all of the major talks shows is actually taking the entire heat for an industry-wide problem? That would make Toyota the hero for coming forward before anyone else did....
Although if this is the industry standard, doesn't seem like it is fixable for Toyota...so why recall?
I gotta say, my Chevy Colorado shows these same characteristics. Coming to s stop on a patched and rutted street engages the ABS every time, and if I hit it at just the right amount of speed, NO BRAKES. WTF.
Brent, he hasn't stood up and taken heat for this, at least not that I've seen, because this is a completely different recall. The latest one was about the gas pedal, and before that, the floormats. This new recall involves complaints about the brakes on the Prius. But in my opinion, it's not a problem limited to just the Prius, or even to Toyota.
Agreed, early Subaru WRXs had a particularly crappy 'Ice Mode', which led some to actually install an ABS kill switch to remove the ABS function entirely. NHTSA investigated for a long time and never did a formal recall, but one can now get their ABS module reflashed by Subaru to presumably improve the situation. But like you said, it's a problem everywhere; experienced it in my 1998 4Runner just yesterday stopping on an unfamiliar offramp that was bumpy. I guess the throttle doesn't stick, it hasn't rusted out, and the floormats stay put at least :).
Phil in KC
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