Unneeded Automatic Emergency Braking - Again

[Toolworker]

No, this sometimes happened when coming to a stop behind another car, and it thinks I was waiting too long to brake. IE coming up too fast behind another car. But also it happened one time when I sped up behind a car to make a lane change. It unexpectedly jammed on the brakes, scaring the heck out of me, and probably the car behind me, too.

Same here, twice.

It also locked the brakes very briefly once when I was on cruise control and someone cut in ahead of me. That wasn't totally unreasonable.

But I've never seen the warning or heard the alarm. What does it sound like? Is it impossible to miss?

 

[R P]

But I've never seen the warning or heard the alarm. What does it sound like? Is it impossible to miss?

Can't remember.

 

[Wildeyed]

This really just sounds like you have a higher tolerance for close driving than the car does. I had similar braking instances when I first got the car and modified my driving behaviour.

 

[NRH]

Fast, loud, high-pitched beeping. Much more attention getting than the other warning sounds (like lane-keeping assist). Also some red warning on the dash (I forget what that says though).

 

[R P]

This really just sounds like you have a higher tolerance for close driving than the car does. I had similar braking instances when I first got the car and modified my driving behaviour.

Yes, undoubtedly, and like I said, I may have adapted (capitulated) to the car. Hasn't happened for a long time.

 

[Wildeyed]

Fast, loud, high-pitched beeping. Much more attention getting than the other warning sounds (like lane-keeping assist). Also some red warning on the dash (I forget what that says though).

Sounds like the collision avoidance warning(s). The sound escalates in the split second before the emergency braking is applied.

 

[electriceddy]

Fast, loud, high-pitched beeping. Much more attention getting than the other warning sounds (like lane-keeping assist). Also some red warning on the dash (I forget what that says though).

When I first encountered this experience ( a car did cut in front and braked heavily), I was more interested to see (in my rearview) just how large a vehicle was going to smack into me rather than pay much attention to the dash display warnings.
My setting are similar to RP.
Forward collision avoidance (FCA) audio portion has surfaced briefly since, however the warning will allow a quick reaction with the brake pedal to avoid the characteristic braking lock up. I am sure the more recent occurrences I have encountered have been triggered by false detection as explained here in the warning section:
https://www.hkona.com/system_malfunction-371.html
"In certain instances and under certain driving conditions, the FCA system may activate unintentionally"

 

[Wildeyed]

The way I read this it says that if the FCA system is malfunctioning it will not operate at all - and you should get a warning light that is malfunctioning. It doesn't suggest that it can imagine imminent collisions and react to them. I'm not saying it's impossible but I am saying that it appears that there are multiple fail-safes built in.

 

[electriceddy]

It doesn't suggest that it can imagine imminent collisions and react to them

See post 27

 

[Wildeyed]

See post 27

Hmm. Kind of buried in the text. I wonder why they don't elaborate on what "certain conditions" are? The only thing I can say is that every time it's happened to me I was: new to the car, was in proximity to other vehicles and was arguably closer to them or was approaching them more quickly than is optimal - well within my tolerances but (presumably) not the car's. I have never had FCA activate when I was alone on the road. Now that would be a clear indication of malfunction and possibly "certain conditions".

 

[Toolworker]

Fast, loud, high-pitched beeping. Much more attention getting than the other warning sounds (like lane-keeping assist). Also some red warning on the dash (I forget what that says though).

From that description, I would surely have noticed it. But in none of the three instances of brakes locking did I hear that sound.

The manual says there is a first warning, with "a warning chime" and "some vehicle system intervention." "Your vehicle speed may decelerate moderately." None of that happened in any of the three cases. The brakes just locked. It came as a complete surprise.

As I said, my old Volt gave me a collision alert a number of times. I just test drove a Mach-E and got the alert. (In most or all of these cases the trigger was a vehicle on the shoulder with no white line between it and the travel lane.) So I know what they sound like on other cars.

Maybe this isn't FCA.

Does anyone know if FCA activation creates an error code? Torque Pro didn't see any codes.

 

[NRH]

Toolworker, sounds like you're having some sort of different problem. If there's no alert noise, then it's either not FCA, or it's some kind of dysfunctional FCA activation.

 

[R P]

If you take it to a dealer, there must be some kind of diagnostic test they can do to determine if there is a problem or if that is just how it works.

 

[Wildeyed]

I'm sorry if I missed it but have you mentioned if you've had the brake software recall work done?

 

[Esprit1st]

If you have issues with that, you should definitely set the FCA to EARLY!! Do not set it to late!!

If you set it to late, there will only be a short time between it starting to beep at you and when it activates the brakes. That's what late means!! It will potentially scare the crap out of you.

However if you set it to early, it will beep at you way ahead of it actually starting to activate the brakes. We are now talking several seconds! This way you have plenty of time to either slow down a little, or at least be aware that it's thinking it needs to activate.

The algorithm, in both cases decided it needs to intervene. (Simplified) That happens at the same time, just in one case it won't tell you until the very last second (late setting).

Make sure you understand how that works. If you have issues with it you will just make it worse by setting it to late.

 

[R P]

If you have issues with that, you should definitely set the FCA to EARLY!! Do not set it to late!!

If you set it to late, there will only be a short time between it starting to beep at you and when it activates the brakes. That's what late means!! It will potentially scare the crap out of you.

However if you set it to early, it will beep at you way ahead of it actually starting to activate the brakes. We are now talking several seconds! This way you have plenty of time to either slow down a little, or at least be aware that it's thinking it needs to activate.

The algorithm, in both cases decided it needs to intervene. (Simplified) That happens at the same time, just in one case it won't tell you until the very last second (late setting).

Make sure you understand how that works. If you have issues with it you will just make it worse by setting it to late.

I am not really sure if that is correct. Does the Late/Early apply to the braking or the audible warning? Maybe it applies to the braking. I know I tried different settings before but IIRC didn't seem to make much difference. However, since I haven't had the problem now for a long time, I am just leaving it as is with the Late setting.

 

[Toolworker]

If you take it to a dealer, there must be some kind of diagnostic test they can do to determine if there is a problem or if that is just how it works.

Did that the first time it happened, a year ago. So as I said above, I have the dealer's service report stating in writing that "The car is operating correctly." I have other problems with the car and have never gotten a dealer to identify a problem.

I'm sorry if I missed it but have you mentioned if you've had the brake software recall work done?

Recall 199. I'd forgotten about it, but yes, it has been done.

If you have issues with that, you should definitely set the FCA to EARLY!! Do not set it to late!!

I am not really sure if that is correct. Does the Late/Early apply to the braking or the audible warning? Maybe it applies to the braking.

The setting is called "Forward Collision Warning," and the manual seems clear about it. "The driver can select the initial warning activation time in the User Settings in the LCD display." Nowhere does it say the actual braking time is adjustable.

So I'll go with @Esprit1st on this and set it to Early. That said, I have never seen or heard a warning, so am thinking it isn't FCA, or is FCA failing to do what it's supposed to. But maybe on Early it will give a warning next time.

 

[navguy12]

@R P , when it kicked in for you, did you see the FCA message or hear a warning tone? What does the tone sound like - is it distinctive or similar to other warning beeps?

Maybe it isn't FCA that is locking my wheels?

I have been closer to a slowing vehicle on many occasions than I was the two times the brakes locked. I have occasionally had to apply much sharper braking than those situations required. I occasionally saw a warning message on my old Volt, but on the Kona I have never seen an FCA warning message or heard a warning tone. And that's as it should be. FCA should only kick in if there is a genuine emergency. If it does, the driver should say "Boy, I'm glad the car was smart enough to do that."

That's what I say when the blind spot alert or the rear traffic warning sees something that I didn't. It's not what I say when I go to apply the brakes in a totally under control situation and all of a sudden they lock and almost cause an accident.

Random peanut gallery question: is it possible that whatever gremlin is causing your intermittent 12 volt battery issue could also be causing this?

 

[Toolworker]

Random peanut gallery question: is it possible that whatever gremlin is causing your intermittent 12 volt battery issue could also be causing this?

I've had that thought and it makes a bit of sense. But as a lifelong computer guy, my instinct is that if something were causing two such disparate misbehaviors, it would be causing a lot more problems as well.

 

[navguy12]

I've had that thought and it makes a bit of sense. But as a lifelong computer guy, my instinct is that if something were causing two such disparate misbehaviors, it would be causing a lot more problems as well.

Agreed.

However, without being able to see how the individual line replaceable units are actually installed and grounded, it can't be totally ignored.

Sometimes all it takes is a common ground to not be torqued properly to set off seemingly unrelated intermittent electrical problems.