[Mcc]

Hi all,

The regenerative braking on my 2021 XLE was something that was always not perfectly smooth but something I had gotten used to. I felt it actually improved what I called the "struggle a bit after complete stop" smoothness after the last software update last fall after oil service.

A couple of weeks ago, as I was slowing down from exiting a highway, just as I was approaching full stop, it felt like the regenerative braking stopped grabbing momentarily and I violently lurched forward for what seemed like a feet or two. I thought it was a fluke back then and thought nothing of it. It just happened again today as I approached a stop sign - again as I neared complete stop with brake depressed it felt like the brake stopped working for a second and the car again lurched forward violently as if I had lost control for what seemed like a foot. Would have hit the car in front of me if there was one.

Had this happened to anyone? It's certainly quite alarming as it seems random and unpredictable, and I do not relish having to try to explain it to the dealer especially when it's not readily reproduce-able. Just wanted to see if people have heard of this issue on this or other toyotas and has the dealer done anything about it.

Thanks!

 

[Sienna9816]

Unfortunately, this has been observed many times.

Here are a couple of threads on it. There are probably few more.

Brakes feel like they release briefly

Has anybody noticed this. Hard to describe. A sudden feeling like the car isn't stopping when slowing down for a light. I had assumed this was the regen switching to the mechanical brakes but it is quite disconcerting. This happens most frequently when I hit bumps when braking down hill...

www.siennachat.com

Possible acceleration while braking issue

I have a 2021 Sienna Platinum AWD, has about 18,500 miles on it. I purchased it December of last year. I have noticed recently that when I am breaking, occasionally as I’m breaking there’s a sudden jolt, or lurch, forward like the car is accelerating a little bit and I was told by a Toyota...

www.siennachat.com

 

[Mcc]

Thanks for the info - looks like the consensus is that Toyota is not doing anything about it... hopefully that changes as I've started experiencing it after 2 years of ownership and they seem to be occurring more frequently...

 

[pamhar]

Was there any bump or uneven road when it happens?

Most of the times that I have experienced there was a bump or uneven part of the road and fortunately at slow speeds.

 

[Davidoff65]

Was there any bump or uneven road when it happens?

Most of the times that I have experienced there was a bump or uneven part of the road and fortunately at slow speeds.

I think you are up to something. Happened earlier today to me and as I was coming to a stop sign, the bump triggered the behavior that everyone is talking about. It never startled me because I wasn't going fast. I'm not worried one bit about it though. My old V6 Venza Limited behaved somewhat the same but no potholes needed.

 

[Sienna9816]

I have experienced two different kinds of unintended accelerations while braking.
1. During gentle braking on even surfaces. Other conditions often reported with this are slight slopes, while turning, and/or full HV batteries. This is the most common type reported here so far. Speeds around 21MPH are the most common. I have however felt this in rare occasions on 40 or even 55MPH.
2. During braking on uneven surface - ex. speed bumps, or lots of small potholes or road damages after snow etc. From my experience, it feels like a donkey kick - kind of like one or more tires loses traction due to decompression of socks or reduced weight, and than when it gets full contact, I feel a hard kick often coming from the rear wheels. (I have an AWD). Motorcyclist refer to this as highside.

 

[Mcc]

I think you are up to something. Happened earlier today to me and as I was coming to a stop sign, the bump triggered the behavior that everyone is talking about. It never startled me because I wasn't going fast. I'm not worried one bit about it though. My old V6 Venza Limited behaved somewhat the same but no potholes needed.

I am well aware of the "uneven surface slip" behaviour, as well as the "stopping too fast making it seem like I killed the engine in a manual car" behaviour - both of those I've gotten used to and I would classify as just mild annoyances.

What I'm experiencing for the first and second time after 2 years of ownership is behaviour #1 per Sienna9816 - where as I'm nearing a complete stop it seems like the brakes just momentarily fail and the car lurches forward violently before I stomp on the brakes further out of reflex to stop the car from rolling forward more. The first time it happened was at a highway off ramp, second time at a stop sign as I near complete stop. Both times it was super alarming since it's seemingly random, quite violent, sends everything flying in the car and makes the occupants feel like they've lost control.

I'm now coping by stopping sooner and well back of other cars when I'm about to stop, but it does make me lose confidence in driving it too aggressively / too close to others. One thing I noticed is that I am always on ECO mode and the battery seems to be always full recently, so maybe people are onto something with regards to regenerative braking stopping itself from overcharging the battery etc...

 

[Sienna9816]

I am well aware of the "uneven surface slip" behaviour, as well as the "stopping too fast making it seem like I killed the engine in a manual car" behaviour - both of those I've gotten used to and I would classify as just mild annoyances.

What I'm experiencing for the first and second time after 2 years of ownership is behaviour #1 per Sienna9816 - where as I'm nearing a complete stop it seems like the brakes just momentarily fail and the car lurches forward violently before I stomp on the brakes further out of reflex to stop the car from rolling forward more. The first time it happened was at a highway off ramp, second time at a stop sign as I near complete stop. Both times it was super alarming since it's seemingly random, quite violent, sends everything flying in the car and makes the occupants feel like they've lost control.

I'm now coping by stopping sooner and well back of other cars when I'm about to stop, but it does make me lose confidence in driving it too aggressively / too close to others. One thing I noticed is that I am always on ECO mode and the battery seems to be always full recently, so maybe people are onto something with regards to regenerative braking stopping itself from overcharging the battery etc...

I would get it checked out at dealership. Very few people have reported the split second pause in brake as violent, or easily noticeable by passengers. Yours might have something else going for it. Some very early 2021s had a TSB around brakes. It is mentioned in other threads.

ECO mode is another common condition mentioned earlier. May be try Normal mode just for the hack of it?

 

[cougarhound]

Yea I was going down a steep hill the other day when it did it. I'm used to it but this was the most memorable incident. Lol. I would say it slipped maybe 5ft or so this time.

 

[Chubbysumo]

I would get it checked out at dealership. Very few people have reported the split second pause in brake as violent, or easily noticeable by passengers. Yours might have something else going for it. Some very early 2021s had a TSB around brakes. It is mentioned in other threads.

ECO mode is another common condition mentioned earlier. May be try Normal mode just for the hack of it?

I have. it happens to me several times a week, and happens to my wife's highlander hybrid(2020 platinum AWD) too, a lot more now with the front struts blown out(they have the same drivetrain). I just leave extra distance for braking. I have recorded this behavior on a scantool, and toyota didn't care, and won't do anything about it. sometimes when I hit the brakes at speeds as high as 50mph, nothing happens, and I press the pedal harder, and then it just makes me look like an idiot because it looks like a slammed on my brakes at the last minute, but I didn't, I just kept pushing harder and nothing happened. it didn't even hit regen in the tach gauge either. until there is an accident from it, and someone can extract the stored data showing that the pedal is being pressed, but the brakes and regen are not being applied, toyota won't do anything about it. The same behavior has been reported by my wife's cousin who owns an XLE hybrid highlander AWD. its like the brakes do nothing, but the electric motors get a burst of power instead of regen.

hmmm. Welp, off to borrow an 8000 scan tool again this weekend to see if I can pull more PIDs now that the van has been out awhile longer. maybe I can see power output to motors, never looked before.

 

[pamhar]

I have. it happens to me several times a week, and happens to my wife's highlander hybrid(2020 platinum AWD) too, a lot more now with the front struts blown out(they have the same drivetrain). I just leave extra distance for braking. I have recorded this behavior on a scantool, and toyota didn't care, and won't do anything about it. sometimes when I hit the brakes at speeds as high as 50mph, nothing happens, and I press the pedal harder, and then it just makes me look like an idiot because it looks like a slammed on my brakes at the last minute, but I didn't, I just kept pushing harder and nothing happened. it didn't even hit regen in the tach gauge either. until there is an accident from it, and someone can extract the stored data showing that the pedal is being pressed, but the brakes and regen are not being applied, toyota won't do anything about it. The same behavior has been reported by my wife's cousin who owns an XLE hybrid highlander AWD. its like the brakes do nothing, but the electric motors get a burst of power instead of regen.

hmmm. Welp, off to borrow an 8000 scan tool again this weekend to see if I can pull more PIDs now that the van has been out awhile longer. maybe I can see power output to motors, never looked before.

Your post kind of reminded me of how sometimes I feel I have enough space to slowly stop but then have to press down harder to actually stop and like you said it looks like braking at last minute.

Keep pressing Toyota as you're apt to get something hopefully done vs us owners without scan tools.

 

[Heath]

Was there any bump or uneven road when it happens?

Most of the times that I have experienced there was a bump or uneven part of the road and fortunately at slow speeds.

same here

 

[Heath]

I would get it checked out at dealership. Very few people have reported the split second pause in brake as violent, or easily noticeable by passengers. Yours might have something else going for it. Some very early 2021s had a TSB around brakes. It is mentioned in other threads.

ECO mode is another common condition mentioned earlier. May be try Normal mode just for the hack of it?

Your wrong buddy manny people have experienced it. Ive been going through the same thing for 2 years. Many threads on here in regards to this topic. You can see mine about a year and a half ago i spoke about this. I have the platinum edition. It feels like the brake lets off and the pedal looses some pressure. Yes mostly happens when you hit a small bump, pot hole or uneven pavement.

 

[Heath]

Hi all,

The regenerative braking on my 2021 XLE was something that was always not perfectly smooth but something I had gotten used to. I felt it actually improved what I called the "struggle a bit after complete stop" smoothness after the last software update last fall after oil service.

A couple of weeks ago, as I was slowing down from exiting a highway, just as I was approaching full stop, it felt like the regenerative braking stopped grabbing momentarily and I violently lurched forward for what seemed like a feet or two. I thought it was a fluke back then and thought nothing of it. It just happened again today as I approached a stop sign - again as I neared complete stop with brake depressed it felt like the brake stopped working for a second and the car again lurched forward violently as if I had lost control for what seemed like a foot. Would have hit the car in front of me if there was one.

Had this happened to anyone? It's certainly quite alarming as it seems random and unpredictable, and I do not relish having to try to explain it to the dealer especially when it's not readily reproduce-able. Just wanted to see if people have heard of this issue on this or other toyotas and has the dealer done anything about it.

Thanks!

Same exact thing here dude for two years. Ive been on multiple threads here trying to figure it out. Toyota even told me the last update on the van was going to fix that problem. Now it happens at least 3 times a day to me. It can be pretty scary. It freaked my wife out. We should get a petition going.

 

[cougarhound]

I don't think they'll ever do anything because it seems to be a common problem across all manufacturers. Maybe keep it in sport mode it it bothers you that much. I drive it in regular mode. Doesn't really happen that much.

https://www.reddit.com/r/TeslaModel3/comments/rvho12

 

[Sienna9816]

Your wrong buddy manny people have experienced it. Ive been going through the same thing for 2 years. Many threads on here in regards to this topic. You can see mine about a year and a half ago i spoke about this. I have the platinum edition. It feels like the brake lets off and the pedal looses some pressure. Yes mostly happens when you hit a small bump, pot hole or uneven pavement.

I am specifically referring to violent **** in your pants kind of accelerations. IIRC, most posts in various threads are about accelerations that were unexpected, scary but not necessarily moments away from accidents. Those kind of reports around here are relatively few.

 

[Sienna9816]

I have. it happens to me several times a week, and happens to my wife's highlander hybrid(2020 platinum AWD) too, a lot more now with the front struts blown out(they have the same drivetrain). I just leave extra distance for braking. I have recorded this behavior on a scantool, and toyota didn't care, and won't do anything about it. sometimes when I hit the brakes at speeds as high as 50mph, nothing happens, and I press the pedal harder, and then it just makes me look like an idiot because it looks like a slammed on my brakes at the last minute, but I didn't, I just kept pushing harder and nothing happened. it didn't even hit regen in the tach gauge either. until there is an accident from it, and someone can extract the stored data showing that the pedal is being pressed, but the brakes and regen are not being applied, toyota won't do anything about it. The same behavior has been reported by my wife's cousin who owns an XLE hybrid highlander AWD. its like the brakes do nothing, but the electric motors get a burst of power instead of regen.

hmmm. Welp, off to borrow an 8000 scan tool again this weekend to see if I can pull more PIDs now that the van has been out awhile longer. maybe I can see power output to motors, never looked before.

Missed to tag you in my post above. I am not referring to milder versions of this. I experience it more often than I like too. Not as much as you do because I barely put 20-30 miles a day vs your 400+.