braking in reverse

Mine only seems to do it when first starting up. Never had it happen at road or highway speeds, only when pulling away from a parked position. Feels like you're stepping on a brick and there's NO forgiveness in how hard the brake pads grab. I do have to wonder if Toyota reads these forums...seems like there's something going on here that many owners have now expereienced that warrants a lot more attention than releasing zipties for floor mats...

 

When it happened to me going forward, I was leaving a grocery store parking lot. Same low speed, partial release of the pedal situation as when it happens in reverse.

 

I guess I may be the first UK owner to post here on this problem. But yes it happened to me twice yesterday whilst driving slowly out of a car park (or should I say parking lot). I thought it may have been my driving, but then my wife went out in the car and also experienced it once. Car has done around 1300 miles and this is the first time its happened.

 

The only way we are going to get this fault fixed is if enough people report there experience to Toyota. There are at least two of us in Australia who have exprienced this problem and we have made Toyota sit up and take notice.
Please do the same in the UK, BlackSpirit. Report it every time it happens.
My gut feeling is that it is a computer software fault. I have no evidence that it is so don't be alarmed. If it is a computer glitch what else can be affected?

 

It happened to me the first time last night in a level, indoor parking garage. I had no idea about what's going on until I read this post this morning. Toyota needs to resolve this issue.

 

I had it happen this past Monday for the first time. Got ours early July. Think we have around 6,666 miles or so. Was parked in our driveway which has a slight slope to it. Just got done washing it. Slowly backed up to get it lined up to put in the left side of the garage and it jerked like crazy. Having previously read about it on this forum I knew what was happening. I just came to a full stop, waited a second and then continued backing and all was fine. I was backing up slowly because a lady and a small child were walking on the sidewalk going up the hill.

Would not like to experience that backing out into traffic or between parked cars, so hope it doesn't happen again.

Will be interesting to see if Toyota figures this out and lets us know why it happens. Next time I bring it in for an oil change, I'll have them log it on my record.

 

2010 Prius "package" III

This is the closest description of whats happening to me except for the hill. This happens to me on flat ground.

Something I noticed is the brake slowly pulsates, kind of like me pumping the break every second or so (except that the car is doing it) . It causes the car to jerk around. Its almost like the master cylinder looses pressure and then repressurizes.

I sure hope I don't run over some pedestrian because of the brakes. This can be a huge problem for Toyota.

I called the Customer Experience Center but I get more of a feeling that this is where complaints go to die more than helping. I'll be bringing my car into the dealer and if they don't fix it after 3 tries, I'm envoking the lemon law.

 

It happened to me for the first time yesterday, while backing out of a parking space. The space I was in was inclined toward the rear of the car, so I put it in reverse and just let it roll back. Every time I touched the brake to slow the car, the brakes grabbed tightly and jerked the car to a stop. Quite annnoying. I have a II with about 2,400 miles on it.

 

I've had this occur, both in forward but more oftenin reverse. As I approach 10K on the car, I've noticed that it hasn't happened in a long time. Anyone else experience same?

- Tim

 

I'm at 5k and it is happening less often as time/miles go on. That's a gut feel as I have not documented it every time it happens.

 

THE BACKUP BUG - UNEXPECTED ACCELERATION

Just yesterday, my Prius-III backed up with sudden unintended acceleration, with my foot only on the brake pedal. No, the accelerator pedal was not "stuck" or being touched in any way. The parking spot was level.

I recognized what was happening because it happened once before, just over 2 months ago, just a few days after I got the car, when I was backing out of an inclined driveway. Perhaps insignificant, but both times, I had a passenger in the passenger seat.

I suspect that some unusual element of the timing of turning the car ON, and shifting into Reverse, and possibly the internal state of the computer and the hybrid power system combine to produce this "abrupt" reverse acceleration as I am gently easing off my foot pressure on the brake pedal. Others describe this as an annoying "Abrupt Braking", and the abrupt braking effect does occur, but only in response to the much more DANGEROUS "unexpected, unintended" reverse power (acceleration), to stop the car motion. No matter how gently the brake is eased further ON to stop, the stop is "abrupt", not smooth.

Yes, in this case pressing the brake gently, just a little, stops the car, but with a big "Jerk" (the Abrupt Braking effect). Then, shifting into Neutral and then to Reverse again "resets" the software so that further backing is the normally expected gentle movement of the car.

However, the unexpected "jump" backward (due to the unexpected power and acceleration) might have caused an accident, crashing my car into anything behind it. This is DANGEROUS.

And, after the crash, who would believe me when I said, "The Prius-Backup-Bug did it, not Me!"?

Sincerely trying to help Toyota have a better Prius,
Gary ..., PhD
Prius-III + Nav, made July 2009 in factory "5"

 

I have experienced the brake grabbing problem on more than one occasion. When it happened yesterday I was backing out of a parking space where I could not see behind me well, and had to move very slowly.

 

I'm so glad I found this topic! Have had my Gen III nearly 3 weeks--have under 700 miles on it. Saturday night I experienced the grab--thank goodness not as severe as many here. It had been parked on an inclined driveway at a party. It grabbed when I first used the brakes. This house is just over the crest of a hill--dangerous spot. Can back enough to then pull forward on the shoulder before going into the road, and it grabbed in forward also. Figured it was just me. So far that is the only time it has done it. It was OK at the first stop sign a couple of blocks down the road. Thanks to ALL!

 

I've reached the point where I know when it will happen. Every time it's happened to me it's been when I sat in the car a minute or 2 before turning it on: at the dealer, as the salesman explained some things to me; at the mall, going through a bag of items I just purchased; writing a check I'm about to mail; chatting with my passenger before I power up; eating a burger I just bought at Sonic, etc. The last few times I thought to myself, "um, I didn't turn it on right when I got in, so I'll probably experience the jerking," and sure enough, I do. Now I turn the car on right when I get in, even if I'm not expecting to drive off immediately, and I haven't experienced it since.

 

Pugsy,
I have been trying to find the timing combination that will
reproduce this problem.
I thought it happens when I drive too soon after I turn the car ON.

I will try your "sit-wait-ON" method, and maybe a
"sit-wait-ON-move-quickly" variation.

I am SURE that this is NOT related to the "gas" pedal being physically stuck down.
Thanks.

 

Its only happened to me on one occasion.
I has stopped for a few minutes in a steep uphill driveway off a cul de sac,to drop a friend off.

When I tried to back slowly out into the cul de sac (no throttle as the driveway was very steep), the brakes would not modulate. They were either off or grabbed tight. Off was not a good option as the space was very tight and I had to turn sharply.

IIRC, I had stayed in the car but I'm not sure if I left the car in drive, put it in park or turned it off.

 

I am finding this is what triggers it for me. I drive to pick my wife up at the train station. I pull in a space and turn the car off. The car then sits 5 minutes give or take before I turn the car back on. If it is going to happen, this is it. The parking lot is flat and level. I don't think an incline has anything to do with it. I think it has to do with turning the car off and turning it on too soon again.

 

I have also experienced the violent locking of the brakes on my 2010 Prius. I just press the brake pedal about 3/8" and they lock so hard that the car rocks on its suspension. This happened a lot while backing out of parking spaces when the car was new. That has diminished recently, but I had my first lock-up while going forward yesterday. The car now has about 4,500 miles on it.

This has always happened while backing out or going forward out of parking spaces, never while actually driving. It's pretty erratic, so it's hard to figure out exactly what causes it. It doesn't seem to be related to how long the car has been parked. Yesterday I was sitting in the car talking to a friend before turning the car on.

My best hunch is that it happens when I put the car in gear before its system has booted completely. It's possible that I tend to start up the car more hastily if I've been sitting and talking first. Today I counted to about 25 after all of the warning lights on the display had gone off and the gasoline engine had kicked on, and had no problems. Unfortunately one day's experience doesn't mean much.

 

I had this happen to me a few days ago. Backing out of a parking place downhill, it seemed that the motor was producing more torque than normal, and I was unable to modulate the brakes, they would grab quickly when applied. After moving forward and backing again the problem went away. The car had only a little over 100 miles on it then, and only 300 miles now and has not had a problem since. I was more worried about the extra acceleration than the grabbing of the brakes; several others in this thread mentioned a greater acceleration, so maybe this is also part of the problem.

 

Well - just adding another me too (well not me - my neighbor). Neighbor bought a 2010, and the other day we were talking about our cars - she mentioned that it acts strangely sometimes when backing up - something about the brakes. I haven't noticed it on mine though.