For those of us who don't particularly like loss of braking, no matter minimally brief, in a moving vehicle, I was wondering if there may be a workaround to limits or prevent experiencing the braking dropout. Here are some ideas: Turn off Eco Mode Turn on Power Mode Keep the car shifted into regenerative "B"raking to limit/prevent switchover of braking style Brake harder or softer Ideas or comments?
I am concerned the "fix" that Toyota will roll-out will impact gas mileage. I like your ideas for the fix. Each time this occured I was in EcoMode and breaking soft to medium at 30-35 mph.
Personally, I don't see how a fix will change fuel economy IF they simply command the hydraulic brakes to replicate the force that regen was creating. If they, instead, command some friction braking along-side light regen, then I do agree this will cause a decrease in performance. Until Toyota officially acknowledges the problem, we can only speculate on the potential fixes. That being said, if we can compare to the fix already included in Jan-2010 or newer cars and their economy, we may be able to understand the impact.
I'm making up the following out of whole cloth, but here's a guess: The problem appears to be brake "drop out" during the changeover from regen to friction. It would make sense, then, that the cure might be: Ensure that one system starts up before the other disappears. That would suggest that HTMLSpinner's scenario of one alongside the other might be what Toyota is doing. My prediction: The 'dual braking' time will be so short and occur sufficiently infrequently that the effect on MPG will not be noticible. It will disappear into all the noise of differing road conditions, temperatures, windspeeds, etc.
The workaround is fairly simple: if you feel like the brakes are not doing the job, press harder. I'm not kidding; that's all it takes. Tom
Tom, having experienced this, you are completely wrong. If it occurs it is not likely to cause an accident, but by that time its too late. You must add extra stopping distance. It appears that if you know it may happen, take your foot off the brakes so that you are not in the regen region. Alternatively brake hard enough to be in the hydrolic region. Once you pass this the brakes appear to be fine. Knowing this the odds of me getting in an accident are very low. I am afraid of lending my car to anyone until the software is fixed.
Here's another workaround: shift into neutral before you brake. This de-activates regenerative braking any forces the cars to use conventional brakes from the get-go, so there is no loss-of-braking switch if you lose traction.
This sounds very similar to the problems Metro Transit in Seattle had with our then new 60' electric trolley busses in the late 1980s. They would experience a skid under certain conditions, primarily on wet roads and while the central wheels (the drive wheels) passed over something like a bump or a man hole cover, that caused the regen brake system to drop out. IF the driver stayed on the brake pedal he/she would continue on into the air brake system and the bus was fine but it was an uncomfortable situation for the driver. As I recall, the fix the shop adopted was to reprogram the regen system so that the friction brakes started being applied earlier. When the regen system cut out the friction brakes were still at least partially on and the "feel" to the driver was much improved. Maybe Toyota needs to contact Seattle Metro Transit to ask about those problems and the fix that took care of the problem 20 years or so ago.
The solution is very simple. PRESS harder on the brake pedal. This will bypass the regen system and engage the friction brakes sooner. The other option is to leave more space then coast with little or no braking.
While I 100% side with "leave more space" and "watch your speed", there are certain situations where quick braking is warranted even with adequate following distance. Not every panic stop is because the guy in front of you is slowing down.
I agree shift into neutral. If you already experienced the brake problems at a certain point such as dimple, bump, steel plate and others, I believe you'll be safe to shift into neutral before you pass the point. Ken@Japan
But does this ever happen on a panic stop, either in one that starts hard or in one that begins with light-to-moderate regen braking and then escalates?
I hope you have some tarmac/concrete roads in Texas and not only potholes, manholes and big scares . Remember, the brake loss situation appears only when wheels lost the contact with road surface momentary.
Nah, I had it happen on a hot day, dry, smooth roads. There could have been a little gravel, but it wasn't much. It's not necessarily easy to reproduce, either.
First, I agree that Toyota needs to adress this problem quickly and surely. It sounds as if some tweaking of the software will do it. Secondly, there are serious differences among drivers, including but not limited to generational differences. When I started driving, there were no ABS brakes, and most cars had drum brakes and a single master cylinder. With drum brakes, one trip through a pretty deep water puddle and you had COMPLETE losss of braking for long distances. A leak in the fluid lines could also cause complete loss of brakes, which you MIGHT be able to recover by "pumping" the brake pedal. And on wet or icy roads, you learned to pump the brakes to stop. Jamming the pedal would lock up all four wheeels and you would go into an uncontrolled skid. In short, you had to be able to DRIVE to car, under varied circumstances. When "Warning" lights replaced gauges on many cars, we called them "Idiot" lights, because they assumed a very low level of understanding and skill on the part of drivers. Today's young drivers expect to press the brake pedal and come to a quick, controlled stop--no matter what. Today's car makers must meet that standard. Because I (and my wife) learned to drive trusting my own skill and attention more than any automatic systems, the brake problem has so far seemed insignificant to me, personally. Nevertheless, since many if not most of today's (younger) drivers expect the car to do most of the "thinking" if not driving, I hope Toyota fixes the problem quickly. We have an appointment to have our 2010 looked at on thursday.
You got me wondering whether Eco mode is where the problem lies? I used to use it a lot but haven't done recently. Also, the braking issue has occured to me about 4 times but not recently despite using the same roads. Could it be as simple as Eco mode causing the problem and sticking to normal mode solves it? Or is that just too simple?
I completely agree. How the heck is a driver to keep this in mind while operating the Prius? I mean, already we must balance the vehicle operation while tuning the sound system, tweaking the AC or heat, checking through the MID, look through the nav screen, sipping our favorite beverage, smoking or chewing, grooming in the vanity mirror, look for things in the glovebox or console, chat with a passenger, check for cops, adjust the driver's seat, swear at other drivers, brush dust off the instrument panel and...of course texting. How can we possibly leave more space in front or allow for braking distance from the cars ahead? We have enough to do while driving already!!!
