ACC quirk turns dangerous

  • Thread starter Thread starter KClark
  • Start date Start date
  • Replies Replies 39
  • Views Views 4K
K

KClark

Active Member
A couple of months ago I wrote about a quirk where the ACC sometimes is very sensitive to cars in front of me as they exit our lane to the right. I've had several occasions when my car has sharply braked as that has happened.

Today I was on a straight stretch of freeway, the traffic was light and the road was dry. I had ACC set to 65 and was going that speed. There was no one in front of me in my lane for several hundred yards. There was a car in the lane to my right about 3 car lengths in front of me. That car exited the freeway at an off ramp and as it left its lane my car suddenly and sharply braked from 65 to less than 50 in just a few seconds. There was a car in back of me that had to slam on its brakes to avoid an accident so it was dangerous to them, but it was also dangerous to me (aside from almost being rear ended) to have my car suddenly and for absolutely no reason behave so erratically.

This is more than an annoyance, it is a danger to people driving near me, and I want to report it to someone but I'm not sure who. Any suggestions?
 
Sounds like you need to have the car serviced. Something is wrong with either the radar or the camera... or software?
 
KClark

Glad nothing serious happened.

Generally the best place to start with a concern is https://www.nhtsa.gov/

Other sites such as carcomplaint.com are useful to other drivers but not the official reporting path to the government agency responsible for these types of complaints.

Of course contacting Honda USA is also prudent.

Hope this helps.
 
Thanks for that link. I am coming up on my first oil change in about a month. I'll talk to the dealer about this. I'm going to the dealer because the first two oil changes/service were included in the purchase.
 
Was it a left exit? That would explain it.

Seriously though, can you describe the situation a little more? How many lanes on the road? Which lane were you in? Was the other car in the deceleration lane? In my mind, 65 to 50 in a few seconds does not sound extreme.

Please don't contact the NHTSA until you've given Honda a chance to investigate. For all anyone knows it could have been some bird poop on the sensor.
 
4 lane freeway, I was in 2nd lane to the right, other driver was in the far right lane. Off ramp was to the right. I was there, 65 to under 50 in a few seconds was quite extreme, and I think the guy in back of me that slammed on his brakes thought it was extreme as well. The quirk that I can have patience with is when the ACC is set and there is a car relatively close in front of me in my lane that changes lanes to our right, sometimes that triggers braking in my ACC, others in my original thread had experienced something similar. This was not that quirk, no one was in front of me, this was dangerous behavior for me and for people around me that was completely unexpected and unnecessary. I'll report it to anyone who will listen.
 
If the car behind had to slam on their brakes they were too close in the first place. On exits that are just a widening of the lane until the crash barrier stripey triangle, the computer can only assume it's a wide lane. If the exiting car slows down, it'll slow down to match. Dedicated exit lanes don't have this problem. Consider staying in next lane over from exits where possible if it is a problem for your driving style. Also, remember ACC is still CC. It ain't self-driving. Keep your foot by the pedals to override when necessary.
 
We've got over 30k miles on our Clarity and I know exactly the situation you are referring to! It seems worse to me when the highway is is turning to the left with a right exit so that the Clarity is somewhat pointing towards the car that has exited and is decelerating. This is one of the exits where I have had the same situation.

upload_2019-5-9_15-18-13.webp

geo
 
I have experienced this as well! Same exact scenario that happens every day while picking up my kid. Albeit I am usually at 40-50 due to traffic. I have concluded this happens when the exit runs too close to freeway almost like a next lane and current lane turns. The car seems to misjudge it.
Edit: I saw the example posted above...YES!!!

In addition to this a minor one is -
not allowing to take exit with out the turn indicator on. On freeways and in city, this happens sometimes though not the recommended driving behavior.

On windy roads with single lane like California-1, I just turn off the features. I have too many calls where the opposite direction car in nice bright California weather is treated as same lane due to curve of the road. The car brakes hard and it is not acceptable at 50+ speeds in my view. (happened twice in Santa Cruz mountains)
 
petteyg359 said:
If the car behind had to slam on their brakes they were too close in the first place. On exits that are just a widening of the lane until the crash barrier stripey triangle, the computer can only assume it's a wide lane. If the exiting car slows down, it'll slow down to match. Dedicated exit lanes don't have this problem. Consider staying in next lane over from exits where possible if it is a problem for your driving style. Also, remember ACC is still CC. It ain't self-driving. Keep your foot by the pedals to override when necessary.
Click to expand...

I think you need to read what I've said again, you're not grasping the situation.

As an aside, yes the guy behind me may have been too close, but why does that matter if I get in an accident because the ACC slams on the brakes out of the thin blue air when no one is in front of me? Is that some kind of Pyrrhic victory I can savor while we wait for the ambulances to arrive?

I was in the next lane over, that's the third time I've said that, there was no one in my lane in front of me. This was a completely unexpected and unwarranted action that has nothing to do with my "driving style" and has nothing to do with being attentive and understanding that ACC is not self driving.

If I have ACC on I should expect that it will react to cars in my lane in front of me, and I've learned from experience to not assume it can drive like I can. But let me say it one more time, there was no one in my lane in front of me. That is why this was so unexpected and so dangerous.
 
Last edited:
K8QM said:
We've got over 30k miles on our Clarity and I know exactly the situation you are referring to! It seems worse to me when the highway is is turning to the left with a right exit so that the Clarity is somewhat pointing towards the car that has exited and is decelerating. This is one of the exits where I have had the same situation.

View attachment 4712
geo
Click to expand...
I've also learned that some curves can be problematic, but this was on a straight stretch of freeway, very light traffic, clear weather and dry road.
 
KClark said:
4 lane freeway, I was in 2nd lane to the right, other driver was in the far right lane. Off ramp was to the right. I was there, 65 to under 50 in a few seconds was quite extreme, and I think the guy in back of me that slammed on his brakes thought it was extreme as well. The quirk that I can have patience with is when the ACC is set and there is a car relatively close in front of me in my lane that changes lanes to our right, sometimes that triggers braking in my ACC, others in my original thread had experienced something similar. This was not that quirk, no one was in front of me, this was dangerous behavior for me and for people around me that was completely unexpected and unnecessary. I'll report it to anyone who will listen.
Click to expand...
If Honda and the dealer tell you to go pound sand and this happens again, sure, go talk to whoever you want. Until it is investigated, engaging the NHTSA is nonsensical. First question they'll ask? Did you talk to the manufacturer? Don't be the parking ticket guy that emailed and called pretty much everyone in his town government except the mayor.

We definitely have different interpretations of extreme. Did your tires squeal? ABS come on? The guy behind you shouldn't have to slam on his brakes to slow down 15 mph in 3+ seconds. If that was the case, the guy behind you was following way too closely.

After reading the rest of the thread, I'm not even sure the car malfunctioned at all. The software/sensor combination does not like it when someone is turning/slowing to turn in front of you. It expects everyone to continue their same movement. It cannot know that the car in front of you is exiting or if the road up ahead has a sharp turn coming and the oncoming traffic is going to pass harmlessly to the side. I've had that happen to me a couple times. It is a bit jarring, but nothing I would call extreme.

Edit: Saw your last post. It sounds a little different. Definitely worth talking with Honda about it.
 
RogerB said:
The software/sensor combination does not like it when someone is turning/slowing to turn in front of you.
Click to expand...

How many times do I have to say it? There was no one in front of me, my lane was empty, the car exiting the freeway was not in my lane. How much clearer can I be? And please, stop the pedantic lectures.
 
Our subaru does similar when a car in front has turned off the road. THe camera's view isn't restricted to just your lane of travel. I punch the gas pedal to tell the car to stop braking which helps to alleviate the situation.

FWIW
 
I just tap the regen paddle to disengage ACC when anything odd happens, and then drive through it.

Did you literally mean "a few seconds"? That is a long time in driving decisions. We make a lot of decisions in driving in one second or less.
 
So the ACC "car" symbol was grayed out on the dash?

I'm wondering if it wasn't ACC itself but the auto breaking system misjuding the car as a potential threat.
 
When it happens to me it's the ACC and I just hit the "go" pedal to get quickly back up to speed. The same effect has happened to me when trucks have drifted towards but not into my lane.

Although I find it annoying, I chalk it up to immature technology and live with it.

geo
 
Last edited:
sniwallof said:
I just tap the regen paddle to disengage ACC when anything odd happens, and then drive through it.

Did you literally mean "a few seconds"? That is a long time in driving decisions. We make a lot of decisions in driving in one second or less.
Click to expand...
Careful. He doesn't want to get into any pedantic lectures.
 
I have limited time driving on interstate highways in the Clarity, but I have had the car exit to the right cause the car to slow, nothing too dramatic yet though. Haven't yet had it when I was not in the same lane as the exiting car, but I can believe it is possible. Maybe your sensor is pointed slightly to the right as compared to dead ahead. Worth asking the dealer to check if they can. I think that maybe there is a setting in the setup for the "sensitivity" of this function (maybe with 3 settings)?
 
RogerB said:
Careful. He doesn't want to get into any pedantic lectures.
Click to expand...

yea, I really did not want to sound that way. And, yes get it checked out.

even highly trained military pilots can fall into the trap of not staying on top of things, fly the plane, not the other way around is what the primary flight instructors always say.

There also seems to be some confusion (in general) about ACC slowing the car down, versus crash avoidance. As noted in that other thread about saved from the person flying out of the driveway, I think the crash avoidance response is quite fast, very different from ACC slowing down the car (for a "real" or "mistaken" reason, as geo says, which happens often).
 
You must log in or register to reply here.
Back
Top