( 
)
Continued from part 5:
The Prius drive system is set up to acquire power to the wheels from either the electric motor or the gasoline engine or both. The gasoline engine is only used to charge the batteries or to provide a mechanical boost to the torque provided by the electrical system. The engine RPM is not directly proportional to the speed of the vehicle. The engine runs at one of 3 RPM settings depending on the power or torque requirement.
The drive system provides a no shift transition to driving with the electric motor and the gasoline engine thru all speed ranges under most flat land driving. When a power increase is needed on normal acceleration, the engine will go to it's intermediate RPM Range as needed and the power is applied smoothly and without any significant change in sound level or pitch. However, when maximum power is called for, the electric motor immediately produces maximum torque and the gasoline engine may not immediately go to it's high RPM range depending on the speed, battery charge condition, steepness of the road grade,etc. When the computer calls for the high RPM setting for the gasoline engine and the engine RPM increases, two things happen.
First the sound level increases in pitch and volume. This is not in direct proportion to any speed change of the vehicle and the sound is sufficient to cause alarm for an individual who is used to having the sound pitch level vary directly with vehicle speed. Second, the horsepower of the gasoline engine is directly related to the RPM. When RPM increases under full throttle, the torque is applied at the wheels after the sound level change and the vehicle may indeed experience greater acceleration than before the RPM increase. When this occurs while the car is on a steep or high altitude, up-hill grade, the car will actually experience an increase in acceleration beyond what is supplied at a lower RPM and it occurs outside the expected sound and time ranges that most drivers expect.
This creates the illusion that something is not working right and that it is dangerous. It appears to be a characteristic of the drive system and is not a problem unless perceived as a problem. The reason I had thought that the original problem was solved by turning off the cruise control may very well have been coincidence because, at the same time as I hit the cruise control handle, I took my foot off of the accelerator pedal. Releasing the accelerator pedal has taken care of the problem whenever it happened in the mountains on my trip.
I cannot say there are not additional problems, but the problem has not occurred except under high acceleration conditions on the freeway or in the mountains. I can make it happen on even a slight grade near home at approximately 5,000 feet above sea level and suspect It could be repeated at sea level under the right conditions. In my case, I now believe that the condition I have had is totally controllable and was a miss-interpretation of what I thought in the very short time when it occurred the first two times.
The time interval was far too short for adequate analysis of the problem. Since I have found a way to repeat it, I feel much more comfortable.
Ingrid Stewart of Elk Grove CA (09/27/07)
i own a 2005 toyota prius and i went through a power steering replacement, and two small batteries and the big battery. I was lucky to have them replaced because i was insured. i'm wondering how many time i have to pay 500 dollars after i run off the insurance. the only time i didn't have any problem i drove it at least 3 times a week. but i have to take the van from elk grove to stockton and im paying right now in two places. i wish i can return it back.
Barbara of Grayslake IL (09/27/07)
I own a 2001 Toyota Prius and have been experiencing the same sudden loss of power while highway driving as described by Thiettranh of Concord. The incident has happened to me at least twice per year for the past few years. I can temporarily resolve the problem by pulling off the highway, turning off the car and waiting about 10 minutes before restarting. The car will restart and run with hesitation and chugging for several miles and then seem to be ok. The warning light remains on until I bring the car in for diagnostic service. I would coordinate the periodic recalls with these service calls and results or the diagnostics directly related to the loss of power problem were inconclusive until this last incident and service call on Sept. 13, 2007. It was determined the accelerator sensor switch is at fault and should be replaced. The part will cost $486.00 + installation and, of course, it is out of warranty. I cannot understand why this wasn't determined to be the problem sooner, while it was still under warranty.
I declined replacement at this time. I will live with the periodic problem for the time being and hope this does not cause a compromise in my safety while driving the car. In the meantime, I am disillusioned with the value of owning a Toyota Prius.
Shancel of San Jose CA (09/18/07)
Twice now in two days my 2006 Aug Toyota Prius (20K miles) has accelerated out of control. Both times it occurred after a hard acceleration (i.e., pedal to the floor). After the second time I intentionally tried to reproduce (since that would be key to getting it fixed) and was able to on my way to work (i.e., the third time its happened now). Once I got into work I sent an email to all of the Toyota Prius owners explaining my experience and that I would keep them informed. One of them forwarded me this link. After reading the link with the reference to the floor mats I inspected my car. I have purchased after market Toyota Prius mats from Toyota. The mat was not centered and it did have a ware mark where the accelerator was rubbing it. And as I manually depressed and released the accelerator it did seem to catch a little. So I moved the mat around and was able to reproduce the problem. The mat did catch the accelerator and hold it. As with others the only way (without knowing what the problem was) to stop the Prius was to bring it to a full stop and press the power button off. And again, with others, the Prius seemed to reset itself. But here is the rub. If it truly were the mat catching the accelerator the previous three times than why did turning the car off solve the problem. There is nothing with the power button that would do this. And yet each time when I restarted the Prius it was fine (i.e., if the accelerator were caught under the mat once the car was turned off the problem did not persist). To me this doesn't make any sense. So what I've decided to do is remove the mat and drive the car for a month to see if the problem occurs without the mat. If this does turn out to the problem than one has to ask why Toyota would sell a Toyota Prius specific mat that would have any potential of causing this problem. If this does not turn out to the problem (i.e., the problem happens again without the mat) than that is bad and others should know. How do I go about updating the site with my experiences within the next month (without the mat)?
Jana of Arcadia CA (09/17/07)
My Toyota Prius lost power and shut down on a Southern Calif freeway. It acted like I ran out of gas but I had a full tank. Pressed accelerator- no power. The red water temperature light came on. It was towed to the dealer. Diagnoses; trans axle malfunction; replaced HV transaxle also replaced drive belt and tensioner. 74,000 miles on the car. No more warranty (60,000 mi). After much nagging Toyota said they will help me with half the costs of the part. This ordeal costs ME $3,490.74. I am disappointed and it could have been a very dangerous situation. Please include me in your investigation.
David of White Bear Lake MN (09/17/07)
I have had the Prius come to a stop in deep snow and then attempt to start up by spinning one wheel at a time for one turn and stopping. I would have been able to keep a less sophisticated car moving in snow such at that.
This is inconvenient and when I get wheel spin over wet paint on a highway while attempting to accelerate fast ahead of oncoming traffic it is very dangerous.
Lupe of Tustin CA (09/17/07)
I have a 2006 Toyota Prius since December 2006, 28,000 miles. 3 weeks ago I went to pick up my daughter from school, I decided to back up my car and wait for her to come out; suddenly my car accelerated while I had my foot pressing the brakes, it was going too fast I had no time to do anything, I crashed onto a wall about 10 ft. on front of me.
The wall was not damaged, and I did not suffer any injuries. The damages on my car are estimated to be $14,000. I have been driving a rental car for the last 3 weeks which my insurance does not cover and my car will take at least 3 more weeks to be ready. I am also terrified to drive it again, especially now that I know that other people went through similar experiences.
Ruth of Charlotte NC (09/14/07)
I purchased a 2003 Prius in Dec 2002, it has less than 55.000 miles on it. Six times the warning lights, engine ck lites, etc have come on. The car has gone from ~25 mph to 19 to 12 -- all the way to 3mph,-> 2->DEAD. Three times I have waited anywhere from 30 minutes to 4 hours and the car has restarted with no problem. Three times my car required towing to the dealership. The dealership has NOT found a problem yet. The last time this happened, my car was at the dealership for 1 week to be driven and checked out. One mechanic did not feel comfortable driving it home because it may 'die'.
Patrick of Grover Beach CA (09/13/07)
Anyone here have a 2001 Prius that has been diagnosed with a failed transmission (transaxle)? Mine is at 91K and started humming a few days ago. I brought it in to a dealer for a diagnosis. They told me it was the transaxle. To replace it with a rebuilt transaxle would cost me almost $5K.
Max of Steamboat Springs CO (09/09/07)
Yes,I really like my Prius, and fully agree with the issue of loss traction and control?I live on a gravel road, and have to park my car in the winter, because of loss of power,traction shuts down, and no way to keep moving when the car shuts down, with or without studded snow tires?
I have to buy a four wheel drive for winter use,even when I bought the Prius they said it was good in snow???
Clinton of Edgewood MD (09/07/07)
I have a 2005 Toyota Prius hybrid car it is the worst investment I've ever made this vehicle has cost me an arm and a leg to maintain. I've already bought three sets of tires and as many alignments costing me 13 hundred dollars and forget how much the oil changes cost. I've taken this vehicle to the dealership three time to have the rack and pinion checked out and they say theres nothing wrong with it this is bumkis because a vehicle should not go through three sets of tires in two years. I own a dodge Dakota pickup for about ten years and only replaced the tires four times and it costs less per tire than the Prius tires.
Marta of North Hollywood CA (09/07/07)
Purchased 2007 Toyota Prius, was told about 45-60 MPG, only averaging around 39-41 MPG. Not really close to what was promised.
Karen of Los Gatos CA (08/31/07)
I have a 2007 Prius purchased the last day in December 2006. After driving the car approximately 1000 miles it, my Toyota Prius Hybrid had an uninitiated full throttle acceleration while driving on an expressway. Startled, I slammed on the brakes, the acceleration fought my braking as I pulled over and turned off the car. Shocked, taking a deep breath what was that?
This first episode I put at the back of my mind because I had just purchased this car from an friend who owns a Toyota dealership and I didn't want to be complaining or concerning him already.
This uncontrollable acceleration? occurred a second time at approx. 13000 miles when I had been stopped at a traffic light, it changed to green and I started to move forward; it took off charging toward the car in front of me. Standing on the brakes, I pulled over and turned off the car. Very frightened, I sat wondering what I should do next. What happens if I turn the car on and it takes off again?
I did turn the car on, and everything was normal. I called Toyota an talked to a sales person and explained this dangerous experience. He confirmed that he was familiar with the problem and also experienced this himself when driving one of the earlier models of the Prius.
He told me to bring it in immediately and was certain that service would know what this was. The Toyota service manager was certain that this very serious and dangerous event was due to nothing more than a floor carpet jamming accelerator pedal.
As I explained to him, I didn't have floor mats when this happened the first time.
Disgruntled, he took my car into service. A day later, they came back to me saying that they couldn't find anything and were certain it was the floor mat and would I pick up the car. This time I called my friend who owns the dealership and sold me the car. I informed him of the problem, he did keep the car for a few more days and asked one of his technicians to drive it home.
I realized that the likelihood of this occurring within a short period was extremely low. Again, they weren't able to find anything and asked me to come pick up my car, suggesting that I put the car into neutral the next time it happens.
That doesn't feel to comforting. Before going to pick up my car and returning the loaner, a concerned friend sent me this link - http://www.consumeraffairs.com/news04/2007/08/prius_acceleration.html.
I forwarded this link to the owner of the Toyota dealership. He too expressed concern and asked me to keep the loaner for a few more days while they get someone for Toyota to look further into this.
At the moment, I'm still in the dealership loaner car. They still have my Prius.
The Prius drive system is set up to acquire power to the wheels from either the electric motor or the gasoline engine or both. The gasoline engine is only used to charge the batteries or to provide a mechanical boost to the torque provided by the electrical system. The engine RPM is not directly proportional to the speed of the vehicle. The engine runs at one of 3 RPM settings depending on the power or torque requirement.
The drive system provides a no shift transition to driving with the electric motor and the gasoline engine thru all speed ranges under most flat land driving. When a power increase is needed on normal acceleration, the engine will go to it's intermediate RPM Range as needed and the power is applied smoothly and without any significant change in sound level or pitch. However, when maximum power is called for, the electric motor immediately produces maximum torque and the gasoline engine may not immediately go to it's high RPM range depending on the speed, battery charge condition, steepness of the road grade,etc. When the computer calls for the high RPM setting for the gasoline engine and the engine RPM increases, two things happen.
First the sound level increases in pitch and volume. This is not in direct proportion to any speed change of the vehicle and the sound is sufficient to cause alarm for an individual who is used to having the sound pitch level vary directly with vehicle speed. Second, the horsepower of the gasoline engine is directly related to the RPM. When RPM increases under full throttle, the torque is applied at the wheels after the sound level change and the vehicle may indeed experience greater acceleration than before the RPM increase. When this occurs while the car is on a steep or high altitude, up-hill grade, the car will actually experience an increase in acceleration beyond what is supplied at a lower RPM and it occurs outside the expected sound and time ranges that most drivers expect.
This creates the illusion that something is not working right and that it is dangerous. It appears to be a characteristic of the drive system and is not a problem unless perceived as a problem. The reason I had thought that the original problem was solved by turning off the cruise control may very well have been coincidence because, at the same time as I hit the cruise control handle, I took my foot off of the accelerator pedal. Releasing the accelerator pedal has taken care of the problem whenever it happened in the mountains on my trip.
I cannot say there are not additional problems, but the problem has not occurred except under high acceleration conditions on the freeway or in the mountains. I can make it happen on even a slight grade near home at approximately 5,000 feet above sea level and suspect It could be repeated at sea level under the right conditions. In my case, I now believe that the condition I have had is totally controllable and was a miss-interpretation of what I thought in the very short time when it occurred the first two times.
The time interval was far too short for adequate analysis of the problem. Since I have found a way to repeat it, I feel much more comfortable.
Ingrid Stewart of Elk Grove CA (09/27/07)
i own a 2005 toyota prius and i went through a power steering replacement, and two small batteries and the big battery. I was lucky to have them replaced because i was insured. i'm wondering how many time i have to pay 500 dollars after i run off the insurance. the only time i didn't have any problem i drove it at least 3 times a week. but i have to take the van from elk grove to stockton and im paying right now in two places. i wish i can return it back.
Barbara of Grayslake IL (09/27/07)
I own a 2001 Toyota Prius and have been experiencing the same sudden loss of power while highway driving as described by Thiettranh of Concord. The incident has happened to me at least twice per year for the past few years. I can temporarily resolve the problem by pulling off the highway, turning off the car and waiting about 10 minutes before restarting. The car will restart and run with hesitation and chugging for several miles and then seem to be ok. The warning light remains on until I bring the car in for diagnostic service. I would coordinate the periodic recalls with these service calls and results or the diagnostics directly related to the loss of power problem were inconclusive until this last incident and service call on Sept. 13, 2007. It was determined the accelerator sensor switch is at fault and should be replaced. The part will cost $486.00 + installation and, of course, it is out of warranty. I cannot understand why this wasn't determined to be the problem sooner, while it was still under warranty.
I declined replacement at this time. I will live with the periodic problem for the time being and hope this does not cause a compromise in my safety while driving the car. In the meantime, I am disillusioned with the value of owning a Toyota Prius.
Shancel of San Jose CA (09/18/07)
Twice now in two days my 2006 Aug Toyota Prius (20K miles) has accelerated out of control. Both times it occurred after a hard acceleration (i.e., pedal to the floor). After the second time I intentionally tried to reproduce (since that would be key to getting it fixed) and was able to on my way to work (i.e., the third time its happened now). Once I got into work I sent an email to all of the Toyota Prius owners explaining my experience and that I would keep them informed. One of them forwarded me this link. After reading the link with the reference to the floor mats I inspected my car. I have purchased after market Toyota Prius mats from Toyota. The mat was not centered and it did have a ware mark where the accelerator was rubbing it. And as I manually depressed and released the accelerator it did seem to catch a little. So I moved the mat around and was able to reproduce the problem. The mat did catch the accelerator and hold it. As with others the only way (without knowing what the problem was) to stop the Prius was to bring it to a full stop and press the power button off. And again, with others, the Prius seemed to reset itself. But here is the rub. If it truly were the mat catching the accelerator the previous three times than why did turning the car off solve the problem. There is nothing with the power button that would do this. And yet each time when I restarted the Prius it was fine (i.e., if the accelerator were caught under the mat once the car was turned off the problem did not persist). To me this doesn't make any sense. So what I've decided to do is remove the mat and drive the car for a month to see if the problem occurs without the mat. If this does turn out to the problem than one has to ask why Toyota would sell a Toyota Prius specific mat that would have any potential of causing this problem. If this does not turn out to the problem (i.e., the problem happens again without the mat) than that is bad and others should know. How do I go about updating the site with my experiences within the next month (without the mat)?
Jana of Arcadia CA (09/17/07)
My Toyota Prius lost power and shut down on a Southern Calif freeway. It acted like I ran out of gas but I had a full tank. Pressed accelerator- no power. The red water temperature light came on. It was towed to the dealer. Diagnoses; trans axle malfunction; replaced HV transaxle also replaced drive belt and tensioner. 74,000 miles on the car. No more warranty (60,000 mi). After much nagging Toyota said they will help me with half the costs of the part. This ordeal costs ME $3,490.74. I am disappointed and it could have been a very dangerous situation. Please include me in your investigation.
David of White Bear Lake MN (09/17/07)
I have had the Prius come to a stop in deep snow and then attempt to start up by spinning one wheel at a time for one turn and stopping. I would have been able to keep a less sophisticated car moving in snow such at that.
This is inconvenient and when I get wheel spin over wet paint on a highway while attempting to accelerate fast ahead of oncoming traffic it is very dangerous.
Lupe of Tustin CA (09/17/07)
I have a 2006 Toyota Prius since December 2006, 28,000 miles. 3 weeks ago I went to pick up my daughter from school, I decided to back up my car and wait for her to come out; suddenly my car accelerated while I had my foot pressing the brakes, it was going too fast I had no time to do anything, I crashed onto a wall about 10 ft. on front of me.
The wall was not damaged, and I did not suffer any injuries. The damages on my car are estimated to be $14,000. I have been driving a rental car for the last 3 weeks which my insurance does not cover and my car will take at least 3 more weeks to be ready. I am also terrified to drive it again, especially now that I know that other people went through similar experiences.
Ruth of Charlotte NC (09/14/07)
I purchased a 2003 Prius in Dec 2002, it has less than 55.000 miles on it. Six times the warning lights, engine ck lites, etc have come on. The car has gone from ~25 mph to 19 to 12 -- all the way to 3mph,-> 2->DEAD. Three times I have waited anywhere from 30 minutes to 4 hours and the car has restarted with no problem. Three times my car required towing to the dealership. The dealership has NOT found a problem yet. The last time this happened, my car was at the dealership for 1 week to be driven and checked out. One mechanic did not feel comfortable driving it home because it may 'die'.
Patrick of Grover Beach CA (09/13/07)
Anyone here have a 2001 Prius that has been diagnosed with a failed transmission (transaxle)? Mine is at 91K and started humming a few days ago. I brought it in to a dealer for a diagnosis. They told me it was the transaxle. To replace it with a rebuilt transaxle would cost me almost $5K.
Max of Steamboat Springs CO (09/09/07)
Yes,I really like my Prius, and fully agree with the issue of loss traction and control?I live on a gravel road, and have to park my car in the winter, because of loss of power,traction shuts down, and no way to keep moving when the car shuts down, with or without studded snow tires?
I have to buy a four wheel drive for winter use,even when I bought the Prius they said it was good in snow???
Clinton of Edgewood MD (09/07/07)
I have a 2005 Toyota Prius hybrid car it is the worst investment I've ever made this vehicle has cost me an arm and a leg to maintain. I've already bought three sets of tires and as many alignments costing me 13 hundred dollars and forget how much the oil changes cost. I've taken this vehicle to the dealership three time to have the rack and pinion checked out and they say theres nothing wrong with it this is bumkis because a vehicle should not go through three sets of tires in two years. I own a dodge Dakota pickup for about ten years and only replaced the tires four times and it costs less per tire than the Prius tires.
Marta of North Hollywood CA (09/07/07)
Purchased 2007 Toyota Prius, was told about 45-60 MPG, only averaging around 39-41 MPG. Not really close to what was promised.
Karen of Los Gatos CA (08/31/07)
I have a 2007 Prius purchased the last day in December 2006. After driving the car approximately 1000 miles it, my Toyota Prius Hybrid had an uninitiated full throttle acceleration while driving on an expressway. Startled, I slammed on the brakes, the acceleration fought my braking as I pulled over and turned off the car. Shocked, taking a deep breath what was that?
This first episode I put at the back of my mind because I had just purchased this car from an friend who owns a Toyota dealership and I didn't want to be complaining or concerning him already.
This uncontrollable acceleration? occurred a second time at approx. 13000 miles when I had been stopped at a traffic light, it changed to green and I started to move forward; it took off charging toward the car in front of me. Standing on the brakes, I pulled over and turned off the car. Very frightened, I sat wondering what I should do next. What happens if I turn the car on and it takes off again?
I did turn the car on, and everything was normal. I called Toyota an talked to a sales person and explained this dangerous experience. He confirmed that he was familiar with the problem and also experienced this himself when driving one of the earlier models of the Prius.
He told me to bring it in immediately and was certain that service would know what this was. The Toyota service manager was certain that this very serious and dangerous event was due to nothing more than a floor carpet jamming accelerator pedal.
As I explained to him, I didn't have floor mats when this happened the first time.
Disgruntled, he took my car into service. A day later, they came back to me saying that they couldn't find anything and were certain it was the floor mat and would I pick up the car. This time I called my friend who owns the dealership and sold me the car. I informed him of the problem, he did keep the car for a few more days and asked one of his technicians to drive it home.
I realized that the likelihood of this occurring within a short period was extremely low. Again, they weren't able to find anything and asked me to come pick up my car, suggesting that I put the car into neutral the next time it happens.
That doesn't feel to comforting. Before going to pick up my car and returning the loaner, a concerned friend sent me this link - http://www.consumeraffairs.com/news04/2007/08/prius_acceleration.html.
I forwarded this link to the owner of the Toyota dealership. He too expressed concern and asked me to keep the loaner for a few more days while they get someone for Toyota to look further into this.
At the moment, I'm still in the dealership loaner car. They still have my Prius.
Guide created: 04/05/08 (updated 04/30/08)
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