[siliconfish]

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, but it happens at other times as well. Sometimes a normal traffic light. I'm braking and then all of the sudden the car feels like it isn't slowing down and I have to mash the brake to keep stopping at the rate I wanted. Wondering if this is normal or if I need to take it in for service.

 

[Boston_Pilot]

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, but it happens at other times as well. Sometimes a normal traffic light. I'm braking and then all of the sudden the car feels like it isn't slowing down and I have to mash the brake to keep stopping at the rate I wanted. Wondering if this is normal or if I need to take it in for service.

Yes. And you’re correct, it’s VERY disconcerting, and VERY concerning. I own multiple hybrids including Teslas, and none of them do that. It feels like they’re kind of “slipping”, and then they catch. It’s garbage…

 

[Vanfam12345]

2021 Sienna Brake Issues

We've had our new 2021 Sienna for just about a week now and have loved it! No complaints except for an issue that has come up sporadically and only 3-4 times this week. When slightly braking for long, drawn out stretches there have been several times when the brakes let up. Not completely but...

www.siennachat.com

 

[siliconfish]

Thanks I missed that thread. But clearly I'm not the only one. I have one of the first 2021 AWD.

 

[wscan]

Thanks I missed that thread. But clearly I'm not the only one. I have one of the first 2021 AWD.

If you have an early build Sienna, there is a TSB that the dealer should do to recalibrate the brake pedal sensor. Details are in the above referenced thread.

 

[Jim19939]

Yes. And you’re correct, it’s VERY disconcerting, and VERY concerning. I own multiple hybrids including Teslas, and none of them do that. It feels like they’re kind of “slipping”, and then they catch. It’s garbage…

It is very strange, I have had my Sienna since February and have no problem with the brakes. I have never experienced this loss of brake feeling. Are there others who have never experienced it?

 

[Vanfam12345]

Are there others who have never experienced it?

Yes. Same here

 

[ET4041]

Me too. I asked the dealer about this and gave them the TSB but they said they couldn't replicate the issue and my VIN is not part of the TSB. I'm in Canada if that matters. I've learned to watch out for this but it's still unsettling when it happens and not normal even for hybrid brakes. I'm completely fine with the operation of the brakes except for this issue.

 

[Orhay]

Get you caliper slider pins checked. If it's not lubricated properly your caliper won't slide and you may have push harder to stop

 

[rustythered]

I have noticed this especially when you are braking and you go over a bump or even just a seam on the road. I don't know what about a bump or vertical jolt would cause the brakes to release, but that is mostry where I have noticed it happen.

 

[JohnHartshorn]

I just experienced this today. Was using a light touch on the brakes to make use of the regenerative braking while approaching a stop sign. At the point it became necessary to apply more brake to avoid running the stop sign there was a brief moment when the brake pedal felt like there were no brakes before the mechanical brakes kicked in. It did cause a quick pucker if you know what I mean.😁

 

[Heath]

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, but it happens at other times as well. Sometimes a normal traffic light. I'm braking and then all of the sudden the car feels like it isn't slowing down and I have to mash the brake to keep stopping at the rate I wanted. Wondering if this is normal or if I need to take it in for service.

Yes it has happened to me as well. I just brought the 2021 Sienna Platinum edition about two weeks ago. I notice this happens especially when I hit a pot whole while braking. It kind of feels as if I slipped on ice for a quick second. It is a little scarry the times it has happened to me. Almost feels like the brakes let up.

 

[Dimitrij]

Yes. And you’re correct, it’s VERY disconcerting, and VERY concerning. I own multiple hybrids including Teslas, and none of them do that. It feels like they’re kind of “slipping”, and then they catch. It’s garbage…

I have heard that Tesla hybrids don't need brakes at all

On a serious note, the transition from regenerative- to friction braking and back should be seamless and instantaneous, and if your van doesn't do that it should be fixed while still on warranty.

 

[CuriousCasserole]

If you run into this issue and feel that it is a safety hazard, you can report your experience to the National Highway Traffic Safety Administration at Report a Safety Problem | NHTSA. If there are enough reports, they will start an investigation and get Toyota to take corrective action if a widespread defect is found.

 

[MattyB]

If you have an early build Sienna, there is a TSB that the dealer should do to recalibrate the brake pedal sensor. Details are in the above referenced thread.

This is not the same issue

 

[pamhar]

Got it a couple of times as well so learning to brake earlier and coasting to red light or stop.

 

[Selkirklake]

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, but it happens at other times as well. Sometimes a normal traffic light. I'm braking and then all of the sudden the car feels like it isn't slowing down and I have to mash the brake to keep stopping at the rate I wanted. Wondering if this is normal or if I need to take it in for service.

I have experienced this a few times and it is alarming. I haven’t experienced it often enough to determine a cause.

 

[Vanfam12345]

Consensus seems to be it happens when van switches from regen + friction braking over to friction braking only. Tends to feel most disconcerting for those driving their first hybrid.

 

[CAADet]

This is not the same issue

Yeah agreed. This isn’t the same issue as that thread at all.
In fact I get this slippage everytime I go in reverse and try to inch my way back.
I have said before, I have to inch my way into my garage due to the length and the brakes slip everytime.

Try doing an on/off/on/off brake sequence and tell me how your van behaves.

 

[MattyB]

I was at dealership today for 10K service. I was able to re-create the issue for the technician. This are currently no bulletins on this issue per the technician so it is currently in the "this is how the car operates" category. He is putting in a "Customer Voice" notification to Toyota. I recommend anyone having this issue to mention it on next service stop at dealership and request they do a "Customer Voice". I think this is the only way to elevate the issue.