braking in reverse

This happened to me a few times shortly after I got the car. I now have about 4k miles on it and it has not happened recently. I wonder if this goes away after "breaking in" the vehicle?

 

hmm interesting, i noticed this happened to me one time. i was parked on an up-ramp at my work's parking garage perpendicular to the slope. thought it was just me, but i guess it wasn't. will make a mental note if it happens again.

 

I think this is a problem, not a driver issue. I had this happen to me yesterday (first time in 1,200 miles). I was backing out of a parking stall and I could not gracefully put the brakes on. No problems in forwards. I got home and tried reverse and there were no problems.

One thing I distinctly noticed when it happend... normally I get a faint grinding feel/noise when I back up from the friction brakes. When it happened, there was none of that. It almost seems to me that the friction brakes were NOT working and the braking came from the motor. I know the regen braking isn't suppose to happen at slow speeds but that is what is seems like to me. Just something to be aware of next time it happens.

Peter

 

Yes this has happened to me also and it is scary, about to take it to the service center.

 

It happened to me when going forward yesterday, makes me feel very uncomfortable using the brakes.

 

Yes, this happened to me, too, a couple times, when backing up in my driveway after just starting the car. I initially thought it might have something to do with the ICE kicking in. It was definitely a scary feeling to feel the car lurch when gently putting on the brakes. It hasn't happened in awhile but I am going to pay close attention if it does happen again, seeing that it is happening to a lot of you. This can't be normal!

 

Yes, I've had the reverse jerking while braking a couple of times now. And I can be very gentle on the brake pedal so I know it wasn't simply the drivers club footed technique. Next time it occurs I'll try the mentioned remedies.

radio

 

+1 on the grippy brakes at 1100 miles. Happened coming out of a driveway that was at a ~10 degree incline.

So far it has happened only once.

 

Wow, had this happened to me once. I thought it was just me but finally someone posted this and now everybody comes forward. This problem isn't that bad, just that it makes you look silly when backing out of the parking lot.

 

ya it happend to me a few times too, my girlfriend was sitting next to me and kept telling me stop doing that.... i told her its not me its the car. but it happened to her too..

 

This happened to me when I was backing out to do my test drive.

I haven't bought the car yet. I'm wondering if I should wait for the 2011's. Maybe this and a few other bugs will be worked out by next year.

 

Ditto here. We've had our IV for nearly a month with almost 1200 miles on it. Yesterday backing out from a space with a slight incline up, the brakes kept grabbing. My husband looked at me like -what are you doing?! The space was so close to level that I hadn't put on the parking brake. My husband parked in the same area (within 5 ft) several times in the past month and had no problem (no parking brake either). I'd heard about this problem reading this thread but it was the the first time I'd experienced it and I'm the primary driver. It was very odd.

 

I agree it's a problem that should go on Toyota's fix list. It's happened to me a few times, and a couple of them my wife, in the passenger seat, was startled and wanted to know what's wrong.

 

I have had this problem once. Note it not the drivers. I had a 2006 P never happen.. I could not remember the fix I had read so I put up with it until I got down the drive way.. Almost flat drive way..Wife was with me and she was like what the beep are you doing. I at least knew what was going on. I still had to hear my wife tell me to stop it a few times. I think next time I will slide into n and see what happens. Toyota will be a bit nerves about this repair compared to the foggy piece of plastic covering up the AC display.

 

Definitely not a driver issue. I've driven my 2010 about 1200 miles now and it just happened to me for the first time. Strange that a couple other people mentioned the first occurrence at that same point, but probably just coincidence. Anyway, I was pulling out of the same driveway I always pull out of (slightly downhill, fwiw) and the slightest feather touch of the brake pedal would lock the brakes right up - no way to feather it at all.. complete on-off toggle behavior. And I mean it locked them hard - not 'a little grabby' or 'sensitive' - we're talking locked cold. If I'd been moving at more than a creep, it would have caused the tires to chirp. Shifting to P and back to R fixed the problem, but this strikes me as a pretty significant issue. When a 3000 pound machine doesn't stop or go in a predictable way, that is a serious safety issue, even if the manifestations have been fairly benign so far. I'd be surprised if there wasn't a recall to fix this issue in fairly short order.

 

Wild isn't? Catches your attention. Do you recall feeling that the friction brakes where not working but rather the feel of the motor grabbing? I swear when it happen to be, I could not "feal" the friction brakes. When I back up, I normally notice a faint grind from the brakes on the rotor, I didn't feel that at all when this happened.

I wonder what it would be like if it did this at say 30-40 mph going forward? Just a thought...

Peter

 

Wild would be one way to describe it :shocked: I'll go with 'unacceptable' (or something considerably less polite, if Toyota doesn't take this seriously enough). It is surprising, that's for sure, and if it happened at any speed, it would be terrifying and possibly lethal, which is why I'm fairly certain it will be addressed in a recall.

Honestly, I have trouble feeling the difference between the regen and the friction brake, even under normal circumstances. I try to discern between them, I really do, and I'm a very attentive driver in this Prius... slight hypermiler, even (60mpg most of the time). Nevertheless, I'm embarrassed to admit that I just cannot feel the friction brakes kick in. I try really hard to maximize regen all the time, so it could be that I just don't use that much friction brake. But whatever the reason, I can't tell :embarassed:

Anyway, my partner had just taken the car out for a pretty tough drive earlier in the day (she drives it like a 'regular' car), so I know there wasn't any rust on the rotors (good theory though). Honestly, it felt like a malfunction in the brake booster or ABS system to me. It seemed too abrupt to be the MGs - they just don't make that much torque.

The thing that gets me is that this is a brake by wire system, right? If the car is deciding whether to use regen or friction, then there is no fixed, direct mechanical connection between the brake pedal and the master cylinder, right? Even the term 'brake pedal' is really an anachronism at this point... it's just a 'go pedal' and a 'stop pedal' in this car if you get right down to it. So I think what we've got here is a software glitch that is somehow triggering the braking assist feature. Accelerometer value not reading correctly causing the ECU to think you're stopping abruptly maybe? The fact that it can be cleared simply by shifting into park and back to reverse suggests it could be a software routine that is normally reset each time you put it in gear that is causing the problem. So I'm going to go with accelerometer initialization failure... That's my guess, anyway.

 

I had this for the first time a couple of weeks ago after about 1800 miles. The situation was that I parked by the side of the road, turned off for a few seconds, then turned back on and backed up slowly. Brakes grabbed every time I touched them, bringing me to a complete sharp stop each time and no doubt looking like a totally incompetent driver to any outside observer.

An earlier poster mentioned it happened to them after they had turned off the engine for a short time, so maybe this is significant. Perhaps something in the braking system has not totally finished resetting itself after shutdown?

 

It may not be when the engine is turned off for a short time, but maybe related to a short stop? When this happened to me, I parked outside a store and my husband ran in. I kept the car running. He hopped back in and when I went to back out, I got the jerky brakes.

 

Confirming this also. The brakes sometimes get pretty touchy in reverse. Only happened a couple times to me so far.