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Discussion Starter · #1 ·
Hi all,
New member, first post. My car is a 2018 Legacy 2.5i Premium with EyeSight system. It has approximately 13K miles.

While driving at highway speed, my car came to a sudden stop without me stepping on the brake. As the result, another car hit my car from behind. I filed a complaint with the NHTSA:
Recalls | NHTSA.

I posted a 15s dash video here:
I was pressing on the gas pedal through the whole thing but failed to get my car to regain its speed. I was NOT using cruise control and/or the Adaptive Cruise Control (ACC) feature at all.

I created a post at the Legacy forum: https://legacygt.com/forums/showthread.php/car-came-sudden-stop-freeway-286779.html
Someone there suggested that I should post here too. I hope it is ok to do so since Outback and Legacy have many same parts.

Questions:
1) Have you experienced or heard about this issue?
2) What do you think might have happened?
Thank you.
 

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2020 Touring XT Crystal Black Silica
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449 Posts
That's scary as heck and I'm glad it looks like nobody was injured. No idea what the cause might be.
 

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2020 Onyx
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12,676 Posts
There are several things that could cause this:
  • The fuel pump recall where the impeller may fail: https://static.nhtsa.gov/odi/rcl/2021/RCRIT-21V587-9534.pdf
  • False activation of Eyesight automatic emergency braking (should have been accompanied by warning lights, tones, and braking noise)
  • Loss of ignition/electrical
  • activation of e-brake
  • transmission problem
I'd like more information - did the engine stop running completely? Could you re-start the car? More detail please.
 
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Apparently the car that was following (and touched the bumper left rear corner when trying to switch lanes to avoid a full rear-ender) saw the brake lights come on. The brake lights would not turn on if the fuel pump or ignition failed, nor do I think it would happen if the e-parking brake were applied.

The video timing shows the car, travelling at highway speed, stopped in about 3 seconds! I wonder if the e-brake could do that; I think it would take all four wheels, including the important front brakes, to stop that quickly, but open to correction.

"False application of Eyesight automatic emergency braking" seems most likely.

I wonder if the car in the right lane that was being passed somehow spooked Eyesight.
 

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Discussion Starter · #5 ·
There are several things that could cause this:
  • The fuel pump recall where the impeller may fail: https://static.nhtsa.gov/odi/rcl/2021/RCRIT-21V587-9534.pdf
  • False activation of Eyesight automatic emergency braking (should have been accompanied by warning lights, tones, and braking noise)
  • Loss of ignition/electrical
  • activation of e-brake
  • transmission problem
I'd like more information - did the engine stop running completely? Could you re-start the car? More detail please.
Based on dash video, car came to a stop in 3 sec. Would a fuel pump failure do that?
The driver whose car hit me said that she saw brake lights before impact.
Engine was still running right after the collision. However, I could not immediately drive it off to the shoulder. I had to turn off and restarted the car.
After the police finished with us, I was able to drive the car home and did not experience any more issue.
 

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2020 Onyx
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Well it's sounding like it was false activation of Eyesight automatic emergency braking but it should have been accompanied by lights and tones and braking noise, which you haven't mentioned. If Eyesight is braking without those alerts, then this is even more serious than a simple false activation.
 
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Another comment about false activation of automatic emergency braking - some have noted that you can use the gas pedal to continue movement during early emergency braking, like if a tumbleweed crosses your path, but it's also documented that at some point, automatic emergency braking (AEB) will completely ignore/override the throttle.
 

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Discussion Starter · #10 ·
Well it's sounding like it was false activation of Eyesight automatic emergency braking but it should have been accompanied by lights and tones and braking noise, which you haven't mentioned. If Eyesight is braking without those alerts, then this is even more serious than a simple false activation.
I did feel vibrations from the steering wheel. However, just right before the impact my eyes were on the rear view mirror and not the dashboard. There might be audible alerts but everything happened so fast I don't know for sure.
 

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2020 Onyx
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I'm curious now how to differentiate between e-brake activation and eyesight AEB if we omit the AEB warnings.
 

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I understand the e-brake can be used for emergency braking by holding the button for several seconds. Once the car stops, I presume it would remain applied until released manually or by trying to drive off. So that part is a possibility.

However, as mentioned, the e-brake involves only the rear wheels and I wonder if they alone could slow the car that fast. Then there's the appearance of the brake lights (according to the driver of the car behind) which is consistent with the way the automatic braking works, but not the e-brake.
 

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(Australian spec) 2019 MY19 Outback 3.6R CVT.
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legacy*, I have just posted a few comments with questions in your legacygt.com topic here in case you haven’t seen them.
 

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Wonder if the black box so to speak would reveal anything? Also makes me wonder how long an event is stored after an accident when the car is driven after the accident.
 

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This is pretty scary stuff. I would be concerned if they couldn’t find anything wrong. I would be more willing to accept a “this part is broken, all fixed now, you’re good to go” but the fact that everything is good is discomforting.

Perhaps the good people at AutoStop Eliminator could come up with a command to remember the Eyesight inhibit functions.

People are quick to judge the driver behind them for not slowing down. The next time you’re at highway speeds going 70, think about that the recommended good weather dry road following distance is around the “2 seconds” rule. You are going 32 meters or 100 feet per second. Giving the two seconds of space is about 200 feet per at least the NJ DMV suggestions. If someone is going from 100 FPS to 0 in 3 seconds, there is not a lot of margin for error here. It’s almost like our brake lights are outdated, we need an extra brake light for “emergency, full on stop” braking power.

I haven’t had a “false alert” yet, but if I do, and it’s unable to be duplicated or resolved, I will absolutely disable the eyesight system.
 

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2017 2.5i Premium Lapis Blue
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Any rear camera video? It probably wouldn't be helpful but I bet the reaction on the face of the other driver would be priceless.
 

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I'm curious now how to differentiate between e-brake activation and eyesight AEB if we omit the AEB warnings.
At speeds above 30mph, the rear tires would lock up and the car would likely start yawing into a skid.
I've tested engaging the e-brake while under way in a parking lot at low speeds. It was pretty dramatic even then. The system has no modulation. It just puts the brakes fully on when activated.
It's possible the G5 and G6 have more developed systems, but I've never seen any mention of it.
 
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