2021 Yaris emergency braking issue

[Ralph H]

25 minutes ago, Cyker said:

 I have now learned, that feedback pressure is totally false/artificial and has no bearing on how much braking you are doing, and I closed on the car in front much faster than I should have been from the feedback I was getting from the pedal!

 

I’ve noticed the same thing, pedal feel is inconsistent particularly when slowing gradually, as it transitions from regen to real braking it feels like the brakes slightly release and you have to press harder to stop. My old mk3 hybrid never did this but it’s brakes were more grabby than the mk4. 
The story’s here about auto braking have me slightly worried I’ve had a few brake alarms but so far it’s not actually taken over and stopped itself. 

[Cyker]

To be fair, it's generally not a problem unless you're driving in a highly congested city with lots of impatient aggressive drivers and narrow roads.

The system is set up perfectly for what I would loosely define as 'normal' road conditions. 99% of all my false positives have been in London, which is the poster-child for impatient aggressive drivers and narrow highly congested roads (Which the local councils are doing everything they can to make even worse! Yay!)

It's just unfortunate that most of my driving is for work in London  

 

[Mojo1010]

Looks like when I eventually get the MK4 I will have to turn off most of these settings as driving in London. Turn it on when it's being driven out of the city. 

[Cyker]

You just get used to it TBH - I can almost predict when it's going to beep at me and it's rare that the auto-brake actually triggers, as opposed to just warning, although it's a bit of a shock when it actually does!

The irony is you're far more likely to crash in London so I find it hard to turn it off - Two of the times the system has saved me; Once when someone just pulled out of a side-road to turn right without looking properly, and then upon seeing me at the last moment, just stopped fully across the road like a total plonker in the perfect position for me to ram the driver-side door into them (If they'd just continued it would have been fine! Uncomfortably close, but fine!)

The car reacted far quicker than I did and stopped so quickly that there was probably enough space for them to fully open their door (I was too busy swearing and honking at them out of shock and also probably some light bruising of the ribs from the seatbelt locking up - The brakes in the Mk4 are *really* good!!  Morse-so as they fixed the ABS compared to earlier models!!)

Another was someone who either doesn't understand how mini roundabouts work or was very overly optimistic about the performance of their car and, again, just cut in front of me suddenly as I was coming round; This sort of thing is very common and I was half-anticipating it so it was a toss up between whether it was me or the car that got the brakes down first, but it was close!

Because this sort of terrible driving is so normal in London (To the point where I've seen this sort of thing happen with a police car in view and they didn't bat an eyelid), I'm too paranoid to disable the system completely!

TBH I'd just avoid London if you can help it; Between KHAAAAN! and the local councils anti-car policies the roads have become more congested, more polluted and more dangerous and that doesn't seem like it's going to change anytime soon...

 

[anchorman]

The brake pedal feel is replicated on a Yaris.  Unlike other cars it has to have brake assistance when the engine is switched off because you can drive quite a long way on Battery power.  It simulates the effort needed based on pedal stroke and then uses accumulated pressure to deliver accordingly.  It might be a bit off the mark but I’ve driven conventional systems that feel either dead or over boosted to the point it’s hard to control.  

[Cyker]

Yea, AFAIK*, it uses a hydraulic pump to supply brake pressure - the master cylinder doesn't do anything other than supply pressure to a sensor, unless the system fails and goes into its failsafe mode.

I think it still operates with a conventional brake booster, with the vacuum supplied by another electric pump (As you say, the engine isn't always running so can't tap it for vacuum!).

I'm not sure what system it uses to supply pedal feedback - The blurb suggests it simulates pedal force based on braking pressure, but in my experience this isn't the case at all and it just feels like I'm pushing against a spring or something.

 

Edit:

* As Far As I Know  

 

[anchorman]

21 hours ago, Cyker said:

Yea, AFAIK*, it uses a hydraulic pump to supply brake pressure - the master cylinder doesn't do anything other than supply pressure to a sensor, unless the system fails and goes into its failsafe mode.

I think it still operates with a conventional brake booster, with the vacuum supplied by another electric pump (As you say, the engine isn't always running so can't tap it for vacuum!).

I'm not sure what system it uses to supply pedal feedback - The blurb suggests it simulates pedal force based on braking pressure, but in my experience this isn't the case at all and it just feels like I'm pushing against a spring or something.

 

Edit:

* As Far As I Know  

 

It has an electric motor booster, not vacuum.........

 

[Derek.w]

With regards to brake alarm on the odd accasion it shown on the dash it cancels as I  drives the car around a obstical.

(parked car at side of road or approaching rounderbout or junction).