I own a 2008 Prius with 11,000 miles. On two occasions at the same location within a six-week period, I had unintended acceleration which lasted approximately 2 seconds. The first time my foot was not on the gas pedal; the second time it was. An icon showed up on the dashboard which I believe was a picture of a battery. As soon as it stopped accelerating, the icon went away. In both cases I was probably traveling about 3 miles an hour making a right turn. Has anyone else experienced this? The first time it happened, I took it to the dealership, and they could find nothing wrong. They did diagnostics on the engine, but nothing negative showed up. Would appreciate any information.
Yes, I believe I was breaking. Can you help explain to me what brake dropout is? When I checked the manual, the icon looked like a battery. It was on for such a short period.
The skid control ECU on the Prius detects loss of traction when braking. If one of the tires slips, the system kicks on ABS. The brief period when the tires are not grabbing feels like acceleration, although it is really just a loss of traction. Tom
Let me explain the road situation in more detail since the acceleration happened at the same spot. I was turning right off a main road but encounter about 10 feet a secondary road running parallel to the first. The latter is available to all the businesses. So, I have to turn quickly but then slow down to look for traffic on the secondary road. In either case, I am going relatively slowly... about 3 miles an hour. In trying to re-create in my mind what exactly happened, the first time I did not have my foot on the brake when acceleration occurred; the second time I did. I hope that explains better the situation.
In either case, there isn't enough information to offer an informed guess. The "brake dropout" thing is usually noticed at a faster speed, above 8 mph. Tom
I will be heading to that same area in three weeks. At that time, I will check to see, if in fact, I might be going faster than I think (closer to 8 than 3 mph). Thanks for your help, Tom.
I bet Tom is right. The first time you experience this effect it is kinda scary as your brain perceives it as accelerating but actually it's the abs cutting on and off. It will happen at that perfect spot that creates tire hop. Lots of posters here think the abs is to aggressive and is causing that issue. I slightly tend to agree as I have driven many other abs equiped cars and don't ever remember this effect on any of those other cars. It has made me be a little more aware of pot holes and braking. Its just another little quirk to this car. It doesn't happen hardly at all except in very certain conditions. There's an entrance to a gas station in town here that has that perfect bump and its a RIGHT TURN TOO!!! and you have to roll off the road a little brisky to enter the station as traffic is usually fast on your butt. I can make it do it there every time. Scary as hell so I always slow down. Can't remember any other place I regularly hit that does it though. Has to be a nice sharp rut that causes wheel hop and never thought of the right hand turn implication before either. You may be on to something there.... BTW the icon is yellow too and lights momentarily.
Anything on the road that reduces traction can trigger this: water, oil, sand, little bumps, ice, loose gravel,... And turning makes it more likely to happen.
This happens to me almost every day on the way home from work. Just before I get to the stop sign, there is a section of pavement that drops off about 1.5 inches just as I'm turning right. When I am braking over that section, it does feel like an acceleration, but I know it is just a spot where the brakes aren't grabbing. On days that I am lucky enough to not have to come to a complete stop, and therefore not braking over that section, this doesn't happen.
This is a much larger problem. My wife experienced a similar incident at very low speed at an intersection where a full stop is required. As a result of the brakes not responding, her car was sideswiped by a truck. Fortunately the other driver was able to avoid a more serious smash and she was not injured. His truck went through a fence and was totalled. THE ROAD IS SMOOTH and WAS DRY at that point. As a result we won't drive the car and won't sell it privately. There are 60 pages of complaints about the brakes on the 2008 and 2009 Prius on the NHTSA website. I now believe that most of them are real, that they are related to a problem with the ABS software OR the switch from Regen to hydraulic braking, and that Toyota will be forced to recall the Gen 11 as well as the Gen 111 for brake problems,
