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Prius Traction Control Complaints on the Rise

Toyota Can't Get a Grip on the Problem

By Joe Benton
ConsumerAffairs.com

April 20, 2007

Toyota Prius • General Complaints • Acceleration • Availability • Battery • Fuel Gauge • Headlight • Insurance Costs • Service Delays • Tires • Transmission • Traction --- • Happy Hybrid Owners --- Test Drive • Three Lead Feet Meet Little Fuel Sipper --- News • Toyota Ready to Expand Safety Recall Beyond Floor Mats • U.S. Prius Sales Drop 45 Percent • Prius Tops Consumer Reports Best New-Car Value List • Toyota Parks Plans For New Prius Plant • Prius Vandalism On the Rise in California • Toyota Plans Prius Plant in Mississippi • Solar Panels to Power Prius Air Conditioning • Unexpected Problems Confront Prius Owners • NHTSA to Hear 'Silent Killer' Complaints • Reports of Prius Price Gouging Rise with Gas Prices • Prius, Porsche Models Top Most-Satisfied Lists • Should You Buy a Second-Hand Prius? • Winter Weather Warning for Prius Drivers • Prius Again Tops Owner Satisfaction Survey • Prius Helps Toyota Knock Off Ford for #2 Spot • Toyota Recalls Floor Mats, NHTSA Warns Prius Owners • Feds Probe Prius Runaway Acceleration • Prius Owners Report More Unintended Acceleration Incidents • Runaway Acceleration Plagues Prians • Toyota Delays Third-Generation Prius • Sales Top 1 Million but Some Owners Find Prius Doesn't Age Well • Prius Owners Losing Ground in Traction Battle • Prius Traction Control Complaints on the Rise • Prius Stalls in Snow; Owners Steamed • Prius Shuts Down in the Snow, Reader Complains • Prius Supplies Increase as Sales Slow • Prius Discounts Popping Up in Showrooms • EPA Finds Prius #1 in Gas Mileage • Prius Owners Question Mileage Claims • Prius Tops Consumer Satisfaction Survey • Hybrids Don't Always Deliver the Expected Fuel Economy

Toyota is unable to modify the troublesome Prius traction control system without placing the vehicle's sophisticated hybrid drive system in jeopardy, according to a Toyota service technician familiar with the Prius problem.

In a mountainous or snowy areas, the little car can be more than just difficult, Prius owners complain.

"I live in the mountains, up steep hills and dirt roads. I consider the slippage problem with the shutting down of power to the wheels just when you need more not less traction to be a very serious problem and a potentially life-threatening design flaw," a New England Prius owner told ConsumerAffairs.com.

A Toyota representative told the Vermont hybrid driver that the system was "operating the way it's supposed to."

"It became clear that they were resistant to accepting that operating the way it was supposed to was the problem," the owner told ConsumerAffairs.com.

The hybrid's traction control system is managed by a computer program and several Toyota technicians have reportedly asked the automaker to modify the software to allow for more wheel spin before shutting the drive line down.

So far Toyota has apparently refused to provide for the modification.

Toyota spokesman Bill Kwon told ConsumerAffairs.com previously that the traction control system in the Prius could impact performance in snowy conditions but he has insisted the slippage was not a safety problem.

"Prius has TRAC (traction control) as standard equipment," Kwon said. "The purpose of traction control is to help prevent wheel spin and minimize slippage of the drive wheels by applying brakes and/or reducing engine power."

Others familiar with the traction issue in the Prius suggest the Toyota concern is for the safety and reliability of the hybrid system, especially the front axle in particular.

They suggest that Toyota engineers are concerned that if the traction control is turned off or modified, the hybrid system will produce so much torque in the Prius that wheel spin would lead quickly to broken axles and even wheels coming off.

One Prius owner was recently told that this is the reason "Toyota is reluctant at this point to allow for even a moderate amount of more spin by changing the Prius traction control computer program."

Currently the Prius system allows for no wheel spin at all and Toyota continues to brush off consumer complaints about the traction control system.

Several Prius owners have reported to ConsumerAffairs.com that they have warned Toyota of the tentative traction control system in the hybrid.

"Fundamentally Flawed"

"This system is fundamentally flawed in a way that could put people's lives at risk and poses dangers in environments like mine where navigating fresh slippery snow and steep inclines are a necessity," our New England reader said.

The Toyota statement that the Prius traction control system is "working as it was designed" has left more than one Prius owner feeling that the system is operating as designed to "protect the safety of the car not the safety of the driver or passengers."

Recently a Prius owner told ConsumerAffairs.com that he thinks Toyota has created "a potentially life-threatening danger for driver and passengers by preventing the driver from being able to exercise control over the vehicle under hazardous conditions."

Our Plainfield, Vermont, Prius owner is continuing to press Toyota for answers.

"I questioned them regarding whether an override switch was available and learned it wasn't and later saw that this is the solution that others had suggested."

Driving a Prius in snowy conditions takes a lot of getting used to. "I did find in a recent snowstorm that I was able to make it up a friends very steep road (just barely) crawling at about 3 or 4 miles per hour at best," he wrote.

"I do see that it's possible to drive this car differently, flooring the gas peddle to barely crawl and have it work but it was so touch-and-go and had another car been coming (up or down) I wouldn't have been able to move out of the way and probably couldn't have restarted with no momentum from a standstill," he wrote.

Our New England Prius owner has reluctantly concluded that, "it is completely clear that I am unable to trust my Prius in serious snow conditions and I now choose not to drive it whenever possible in fresh snow."

"Yesterday, I was not even able to get the car to move more than a few inches in reverse on my almost entirely flat driveway over just a few inches of fresh, wet snow, even when there was no snow under the car itself," he wrote.

On the other side of the country in Redwood City, California, yet another Prius owner has experienced the same traction control problems with a 2007 Prius.

"The traction control has proven to be very troublesome. If a bump in the road on a hill causes a wheel to bounce the traction control cuts all power and brings the car to a standstill," Ralph wrote ConsumerAffairs.com.

"This makes some roads and driveways passable to all other cars impassable to the Prius. This is a defect and can cause the car to become stuck very easily," he told us.

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