NHTSA Tracking Braking Loss on Prius Hybrids
Dozens of owners of the current third generation Toyota Prius models have filled complaints with the National Highway Traffic Safety Administration about the alleged brake failures they have experienced.
The Office of Defects Investigation has at least 33 complaints that we are aware of from Prius owners alleging a problem or safety defect, often about the design or performance of the braking system, which recharges the battery when the Prius decelerates.
Some owners describe this as unintended acceleration, but a review of the complaints by TheDetroitBureau.com leads me to think that this is an issue about how the braking system is calibrated. Whether this is a safety related defect is ultimately up to NHTSA to decide. The safety agency is authorized to order manufacturers to recall and repair vehicles when ODI investigations indicate that they contain serious safety defects in their design, construction, or performance.
For Toyota, it is another owner satisfaction or quality issue, at a minimum, coming from its most advanced technology vehicle at a time when Toyota is under attack for its handling of safety matters.
Braking performance issues?
In the case of the Prius brakes, it appears that the transition from regenerative braking to hydraulic braking is not transparent to drivers. Under certain conditions, the driver needs to press harder on the brake pedal to obtain the same stopping performance the regenerative system working in conjunction with the hydraulic brakes initially provides. Drivers are clearly upset by longer than expected stopping distances.
“What I, and others have been experiencing, is certainly not “runaway acceleration” or anything to do with pressing the gas pedal,” Robert Becker, an unhappy owner of a 2010 Prius, told TDB.
“But rather the loss of braking power or braking momentum when hitting a pothole, manhole cover, or the like. This requires the driver to press down again harder on the brakes to slow or stop the car,” Becker says.
Becker’s complaint is typical of others that ODI is tracking from owner communications on its Auto Safety Hotline. However, the existence of complaints does not mean the government will ultimately pursue the matter. The next step would be to open up an engineering investigation, a step that has not been taken.
Here is another Prius driver filing: “There have been several incidents in which my car seemed to surge forward while I was in the process of braking and hit a bump, railroad tracks or pothole. Initially, I convinced myself I must have been letting up on the brake when I hit the bump, but when this same thing happened three days ago on slippery, icy roads, I knew for 100% certain I had not let up on the brake. My car surged as I was slowly pulling up to a stop sign and gently braking. I came very close to hitting the car in front of me, had to push down on the brakes very hard, which activated the abs.”
I think what is going on is a combination of design/calibration choices and the compounding effects, forgive the pun, of the low rolling resistance tires, suspension settings and perhaps vehicle weight.
The Prius is arguably Toyota’s strongest image vehicle, dominating the hybrid segment as the best seller with more than 1 million in sales to date, and disproving other automakers’ contentions that Japanese companies only copied instead of innovating.
A Toyota spokesperson initially told TDB that he was unaware of the issue, but Toyota quickly supplied the following statement: “We are aware of the complaints filed with NHTSA. The agency has not opened an investigation. We are investigating the issue based on internet traffic, customer comments to Toyota Customer Relations, and NHTSA complaints. It is too early to speculate the final conclusion(s) of our investigation and subsequent actions.”
NHTSA would only confirm that no recall or engineering investigation is underway. The ODI complaints are a matter of public record, though.
Source: NHTSA Tracking Braking Loss on Prius Hybrids
The Office of Defects Investigation has at least 33 complaints that we are aware of from Prius owners alleging a problem or safety defect, often about the design or performance of the braking system, which recharges the battery when the Prius decelerates.
Some owners describe this as unintended acceleration, but a review of the complaints by TheDetroitBureau.com leads me to think that this is an issue about how the braking system is calibrated. Whether this is a safety related defect is ultimately up to NHTSA to decide. The safety agency is authorized to order manufacturers to recall and repair vehicles when ODI investigations indicate that they contain serious safety defects in their design, construction, or performance.
For Toyota, it is another owner satisfaction or quality issue, at a minimum, coming from its most advanced technology vehicle at a time when Toyota is under attack for its handling of safety matters.
Braking performance issues?
In the case of the Prius brakes, it appears that the transition from regenerative braking to hydraulic braking is not transparent to drivers. Under certain conditions, the driver needs to press harder on the brake pedal to obtain the same stopping performance the regenerative system working in conjunction with the hydraulic brakes initially provides. Drivers are clearly upset by longer than expected stopping distances.
“What I, and others have been experiencing, is certainly not “runaway acceleration” or anything to do with pressing the gas pedal,” Robert Becker, an unhappy owner of a 2010 Prius, told TDB.
“But rather the loss of braking power or braking momentum when hitting a pothole, manhole cover, or the like. This requires the driver to press down again harder on the brakes to slow or stop the car,” Becker says.
Becker’s complaint is typical of others that ODI is tracking from owner communications on its Auto Safety Hotline. However, the existence of complaints does not mean the government will ultimately pursue the matter. The next step would be to open up an engineering investigation, a step that has not been taken.
Here is another Prius driver filing: “There have been several incidents in which my car seemed to surge forward while I was in the process of braking and hit a bump, railroad tracks or pothole. Initially, I convinced myself I must have been letting up on the brake when I hit the bump, but when this same thing happened three days ago on slippery, icy roads, I knew for 100% certain I had not let up on the brake. My car surged as I was slowly pulling up to a stop sign and gently braking. I came very close to hitting the car in front of me, had to push down on the brakes very hard, which activated the abs.”
I think what is going on is a combination of design/calibration choices and the compounding effects, forgive the pun, of the low rolling resistance tires, suspension settings and perhaps vehicle weight.
The Prius is arguably Toyota’s strongest image vehicle, dominating the hybrid segment as the best seller with more than 1 million in sales to date, and disproving other automakers’ contentions that Japanese companies only copied instead of innovating.
A Toyota spokesperson initially told TDB that he was unaware of the issue, but Toyota quickly supplied the following statement: “We are aware of the complaints filed with NHTSA. The agency has not opened an investigation. We are investigating the issue based on internet traffic, customer comments to Toyota Customer Relations, and NHTSA complaints. It is too early to speculate the final conclusion(s) of our investigation and subsequent actions.”
NHTSA would only confirm that no recall or engineering investigation is underway. The ODI complaints are a matter of public record, though.
Source: NHTSA Tracking Braking Loss on Prius Hybrids
