Brake problem on new Corolla

[camellia30]

9 hours ago, TonyHSD said:

Car manual explains that drivers should never let the car in D while stationary because a sudden acceleration can happen. 
 

My car stays in D the whole drive, and i'm stationary multiple times a journey with either:

Foot on the brake pedal

No pedals pressed and brake hold

No pedals pressed and radar cruise control has brought me to a stop

[TonyHSD]

Ok, I am not a Toyota master technician or certified car mechanic but I have worked on few Toyota hybrids particularly the brake system, doing some maintenance work like brake parts change and fluid change etc. In addition to that I look after my car that I also use for my business travel which is a bit more than average for the uk commuter. Previously also driving a Prius as cabby in London and working for the largest Prius fleet at the time, I have some experience with these cars to confirm that once the brake pedal is pressed firmly there is no chance the car can jump forward, actually the car won’t be able to move at all. 
Toyota hybrids has another tricky part with their brakes that is completely different from any other cars I have tried and it’s something all hybrid owners should be aware and remain careful, but this has nothing to do with what the op has experienced. 
The issue with Toyota hybrids brakes is that when slowing down quickly and you hit a pothole and one or more tyres loose grip the car brake system becomes weak and the only way to gain full stopping power again is to fully release brake pedal and press again, something that is not first instinct to a non trained driver. Usually on other cars when hit something and abs is activated the driver will continue to hold the brake pedal firmly and the car will gain stopping power again it that’s not exactly the case with Toyota hybrids. 
Toyota hybrids does not like to loose grip in two major scenarios:

1. When under having acceleration-  damper clutch can slip and trigger hybrid system malfunction error 

2. Abs and ASC can let you have weak brakes and you need to fully release the brake pedal and press again otherwise your brake distance will increase  
However what we seem has happened to the op as unfortunate event is only possible if brake pedal was not pressed. 
When brake pedal is pressed the front brakes has direct connection with the pedal and not electronic therefore no possibility of a software glitch or computer error.

 

[Alan Seddon]

Again, thank you for your input Tony. I was in a gutter but I don’t suppose that can be compared with a pothole! In any event, I will have to put this down to a very unfortunate (or perhaps stupid) experience. When I eventually get the car back, I will be extremely careful after this event. 

[Derek.w]

Reminds me of days before all this electronic brake control systems you released the pedal then reapplied preassure.

[TonyHSD]

4 minutes ago, Derek.w said:

Reminds me of days before all this electronic brake control systems you released the pedal then reapplied preassure.

That’s right. It’s not like you loose all the brakes but it’s a strange and unusual behaviour.
I am not sure why exactly happens like that , perhaps the car cancel the regenerative braking or the electric braking on the rear axle and you only have front brakes which are directly controlled by the pedal as overriding the ecu. Not 100% sure what it is exactly. Another time when brakes can become same weak is when you have wheel speed sensor fault, then regenerative braking is not available at all and rear brakes too so only have front brakes and obviously a red warning and yellow warning lights and messages on screen not to drive. Happened to me twice, I did drive the car for to get home but I was extra careful. 

[TonyHSD]

41 minutes ago, Alan Seddon said:

Again, thank you for your input Tony. I was in a gutter but I don’t suppose that can be compared with a pothole! In any event, I will have to put this down to a very unfortunate (or perhaps stupid) experience. When I eventually get the car back, I will be extremely careful after this event. 

You are welcome.
Let’s hope they will fix the car soon and let you know about it and their theory of what had happened. 👍

[Cyker]

The ABS on my Mk1 and Mk2 were awful for that; There's a sliproad exit off a fast A-road that has a manhole cover right in the braking zone followed shortly by a sharp left turn, and if you brake before it, it's almost guaranteed the ABS will trigger as the wheels go over the manhole cover, which then suddenly takes away half your braking force and makes it feel like you're accelerating towards the lamp post on the outside of the turn!  

I learned to either slow down much more before entering the slip road (A bit risky in traffic as you risk an Audi up the Audi!), or coast over the manhole then brake more afterwards, but they seem to have fixed it in the Mk4 as the ABS no longer does this under normal conditions (It still does it when it's raining or when there's snow, but that's more understandable and expected at least!)

The Mk4's ABS generally seems better tuned and much less prone to manhole-cover-caused false positive ABS triggers than the previous ones, and even when it does trigger, the loss of braking force seems nowhere near as severe as it was on earlier models.

[AisinW]

1 hour ago, TonyHSD said:

Ok, I am not a Toyota master technician or certified car mechanic but I have worked on few Toyota hybrids particularly the brake system, doing some maintenance work like brake parts change and fluid change etc. In addition to that I look after my car that I also use for my business travel which is a bit more than average for the uk commuter. Previously also driving a Prius as cabby in London and working for the largest Prius fleet at the time, I have some experience with these cars to confirm that once the brake pedal is pressed firmly there is no chance the car can jump forward, actually the car won’t be able to move at all. 
Toyota hybrids has another tricky part with their brakes that is completely different from any other cars I have tried and it’s something all hybrid owners should be aware and remain careful, but this has nothing to do with what the op has experienced. 
The issue with Toyota hybrids brakes is that when slowing down quickly and you hit a pothole and one or more tyres loose grip the car brake system becomes weak and the only way to gain full stopping power again is to fully release brake pedal and press again, something that is not first instinct to a non trained driver. Usually on other cars when hit something and abs is activated the driver will continue to hold the brake pedal firmly and the car will gain stopping power again it that’s not exactly the case with Toyota hybrids. 
Toyota hybrids does not like to loose grip in two major scenarios:

1. When under having acceleration-  damper clutch can slip and trigger hybrid system malfunction error 

2. Abs and ASC can let you have weak brakes and you need to fully release the brake pedal and press again otherwise your brake distance will increase  
However what we seem has happened to the op as unfortunate event is only possible if brake pedal was not pressed. 
When brake pedal is pressed the front brakes has direct connection with the pedal and not electronic therefore no possibility of a software glitch or computer error.

 

These phonemena is actually a recall.  Toyota release a recall for reprograming the ABS. The issue is braking on bumpy roads. https://www.cars.com/research/toyota-prius-2010/recalls/  I have not found it for europe recall list. 

[Geoff W]

Going back to Alan's original incident, I was interested to see the press announcement for the 2023 Corolla included this new feature:

"There’s also a safeguard against sudden, unintended use of the accelerator when moving at low speed, with a new acceleration suppression function."

I wonder why Toyota felt the need to add this! 

[Popama]

2 hours ago, Geoff W said:

Going back to Alan's original incident, I was interested to see the press announcement for the 2023 Corolla included this new feature:

"There’s also a safeguard against sudden, unintended use of the accelerator when moving at low speed, with a new acceleration suppression function."

I wonder why Toyota felt the need to add this! 

The scariest part is that they had to add a safeguard and could not fix the existing code. So good luck to those of use without the existing vehicles.

[Cyker]

The safeguard is not related to the issue mentioned (At least I think not!) - I think it's primarily for Americans who get the brake and accelerator mixed up. A surprisingly... not common, but frequent enough issue.

More annoyance to me tho', as very often I do want to suddenly accelerate very sharply (e.g. at a roundabout!) - Yet another thing that will likely conspire to kill me!!  

I really don't like this increasing trend of manufacturers putting in tech that allows the car to unilaterally decide to override what I'm telling it to do. I spent a lot of time and money being properly trained to drive a car, but if they keep catering to bad drivers instead of good ones, all we will have are bad drivers!!

And if it taking control away from me actually causes an accident, will the car get the blame?? I bet not!!

[TonyHSD]

3 hours ago, Geoff W said:

Going back to Alan's original incident, I was interested to see the press announcement for the 2023 Corolla included this new feature:

"There’s also a safeguard against sudden, unintended use of the accelerator when moving at low speed, with a new acceleration suppression function."

I wonder why Toyota felt the need to add this! 

Most likely because a similar incidents has happened to other Toyota cars owners. Todays cars are fully loaded with safety futures that seems helpful but in some cases can be confusing. The brake hold function is one of these and perhaps may have played a role in Alan’s case, or at least as addition to the hill road. 
It is very easy to bring a Toyota hybrid to a complete stop without using the brakes at all, like one pedal drive on other cars and the car will remain stationary with or without brake hold and at this point it is ultra easy for the driver to get confused that his foot is on the brake pedal where actually it’s on the accelerator, and then the sudden acceleration happens. 
 

[Dylanfan]

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

[forkingabout]

11 minutes ago, Dylanfan said:

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

It so people don't activate it then get out of the vehicle thinking it will stay where they left if - it will likely be a liability reason in case the vehicle rolls / drives away by itself.

Also some drivers don't want to use the brake hold function.

[fred88]

4 hours ago, Dylanfan said:

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

Agreed, my previous car was a Passat and auto hold was on by default with a button to turn it off if you wished. For me it worked so well I forgot about it and find it a nuisance on the Corolla having to switch it on each time.

[bigblock]

12 hours ago, Dylanfan said:

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

On my Corolla I have it set up so that when gear shift is in 'P' the brake hold automatically comes on. When I shift to 'D' the brake hold comes off. This means that I never have to touch the brake hold switch at all. So for example at traffic lights I just shift to 'P' and take foot off brake pedal. To pull away I just shift back to 'D' . Simples.

[Cyker]

13 hours ago, Dylanfan said:

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

The thing is, it deactivates if you take your seatbelt off or open the door, for safety reasons, so you'd need to reset it regardless unless you somehow got out of the car without unplugging the belt or opening the door!  

The brake hold is only an enhanced version of hill hold/hill start and not meant to be used for extended periods as it doesn't 'fail safe', unlike the EPB, which will stay locked if the system fails.

 

1 hour ago, bigblock said:

On my Corolla I have it set up so that when gear shift is in 'P' the brake hold automatically comes on. When I shift to 'D' the brake hold comes off. This means that I never have to touch the brake hold switch at all. So for example at traffic lights I just shift to 'P' and take foot off brake pedal. To pull away I just shift back to 'D' . Simples.

I think you've mixed up the brake hold with the EPB - The brake hold never activates automatically when shifting to P as it's just a hold for the hydraulic footbrake. AFAIK only the EPB can be set to dis/engage with the P.

(I'm glad they finally added that feature - It made absolutely no sense for the EPB to not automatically engage when selecting P when they first introduced them!)

[YarisHybrid2016]

On 2/14/2023 at 9:37 PM, TonyHSD said:

That’s right. It’s not like you loose all the brakes but it’s a strange and unusual behaviour.
I am not sure why exactly happens like that , perhaps the car cancel the regenerative braking or the electric braking on the rear axle and you only have front brakes which are directly controlled by the pedal as overriding the ecu. Not 100% sure what it is exactly. Another time when brakes can become same weak is when you have wheel speed sensor fault, then regenerative braking is not available at all and rear brakes too so only have front brakes and obviously a red warning and yellow warning lights and messages on screen not to drive. Happened to me twice, I did drive the car for to get home but I was extra careful. 

On my Yaris, I can tell you exactly.

Normal, "regular" braking is regen only. Lose grip, traction light flashes and it engages the mechanical brakes. Depending how hard you're braking (level vs. downhill) it can under-estimate the mechanical braking force required. If you simply press harder it will respond. I'm not aware of the system being unable to provide limit braking even when the transition is less than ideal. It just feels strange as we are mostly used to regen braking.

[bigblock]

On 2/16/2023 at 7:44 AM, Dylanfan said:

I find it strange that the brake hold system has to be set to on after each engine start. The system works so well, why isn’t it automatically set, or am I missing something?

Look at page 165 in the online user manual. You can have the Parking brake work in auto mode 'on' or 'off' Mine is set to auto 'on' mode. This means I never have to touch the Parking brake switch or use the Brake hold switch at all. I get in car and shift to 'D' and parking brake disengages on it's own. Shift back to 'P' and parking brake is on again and red led is lit on the parking brake switch to confirm this. Hope this answers your question.

[Alan Seddon]

Thanks for your comments bigblock. I will check that out.

I have now registered an investigation with Toyota directly so I’ll let everyone know the outcome. 
It will be a while as my Corolla is still stuck in a body shop awaiting parts to build back the complete front end. 

[50p]

1 hour ago, bigblock said:

Look at page 165 in the online user manual. You can have the Parking brake work in auto mode 'on' or 'off' Mine is set to auto 'on' mode. This means I never have to touch the Parking brake switch or use the Brake hold switch at all. I get in car and shift to 'D' and parking brake disengages on it's own. Shift back to 'P' and parking brake is on again and red led is lit on the parking brake switch to confirm this. Hope this answers your question.

Mine is set as above also

[bigblock]

49 minutes ago, 50p said:

Mine is set as above also

Excellent. It makes things so much easier doesn't it.

[bigblock]

23 hours ago, Cyker said:

The thing is, it deactivates if you take your seatbelt off or open the door, for safety reasons, so you'd need to reset it regardless unless you somehow got out of the car without unplugging the belt or opening the door!  

The brake hold is only an enhanced version of hill hold/hill start and not meant to be used for extended periods as it doesn't 'fail safe', unlike the EPB, which will stay locked if the system fails.

 

I think you've mixed up the brake hold with the EPB - The brake hold never activates automatically when shifting to P as it's just a hold for the hydraulic footbrake. AFAIK only the EPB can be set to dis/engage with the P.

(I'm glad they finally added that feature - It made absolutely no sense for the EPB to not automatically engage when selecting P when they first introduced them!)

Yes you are correct on the brake hold function. I am indeed referring to the main EPB. Sorry for the confusion. I never use 'brake hold' so I didn't think about this switch during my reply.

[Dylanfan]

My parking brake is also set to work when I move into park. During normal driving the parking brake is not being used, that’s why the brake hold is used. My previous car, a Citroen, applied the parking brake whenever you came to a stop, and it came off when you moved off; it was simple and worked automatically. When I bought the Corolla I found the system to be really confusing and now after three years I still wonder why it’s not fully automatic.

[2badmice]

I don't want to cause offence, but if I had a mortgage I would 

On 2/17/2023 at 6:05 PM, bigblock said:

Look at page 165 in the online user manual. You can have the Parking brake work in auto mode 'on' or 'off' Mine is set to auto 'on' mode. This means I never have to touch the Parking brake switch or use the Brake hold switch at all. I get in car and shift to 'D' and parking brake disengages on it's own. Shift back to 'P' and parking brake is on again and red led is lit on the parking brake switch to confirm this. Hope this answers your question.

This is the electronic parking brake you are activating when moving the lever from P to D and vice versa.

 

Hold is to hold the vehicle stationary when stopped at lights or in heavy traffic for example when not using P is required and you are able to take the foot off the brake pedal and then need to depress the accelerator when it's time to move.

 

Set your ACC and be behind a car whilst active and HOLD is set to on.  When you are ready to move forward ACC will tell you to depress the accelerator.

 

Apologies I see your other post.