Scary braking problem

[ChrisH1]

I am new owner of a 2012 leaf. I love the car.
But this morning I had a really scary experience with braking. I was traveling around 25 mph and looked down a moment. Looking up, I noticed the car a ways in front had slowed down a bit, I pumped the brake to equalize the speed, my touch was a bit harder than intended, but I expected the car to quickly drop about 4-5 mph. I got a real scare and scared the ---- out of the car behind when the brakes locked and this rubbing rubber sound emanated. My foot pressure was minimal, but still on the brake... but when I experienced the brake rubber sound I lifted my foot and still the sound continued and the car came to a near stop (walking speed). Of course the car behind me was caught completely off-guard and I'm sure wondered what happened. Fortunately there was enough room so she could stop, but it was close.
As new owner, this caught me completely by surprise. This is definitely a brake operation defect and needs to be addressed. Owners need to be aware of this peculiar brake behavior... or the possibility of this happening. When your foot pressure is released, the car MUST respond and the physical brake MUST let go; only regenerative braking is ok. I was very lucky not to have caused a rear end accident to my car. I was very shaken up as I have never had a vehicle respond like this while braking. I'm not bothered by ABS if it lets go when braking pressure is released, but pumping the brake CANNOT cause the car to come to a near stop after foot pressure or your foot is completely removed from the brake peddle.

 

[leafedbehind]

I am new owner of a 2012 leaf. I love the car.
But this morning I had a really scary experience with braking. I was traveling around 25 mph and looked down a moment. Looking up, I noticed the car a ways in front had slowed down a bit, I pumped the brake to equalize the speed, my touch was a bit harder than intended, but I expected the car to quickly drop about 4-5 mph. I got a real scare and scared the ---- out of the car behind when the brakes locked and this rubbing rubber sound emanated. My foot pressure was minimal, but still on the brake... but when I experienced the brake rubber sound I lifted my foot and still the sound continued and the car came to a near stop (walking speed). Of course the car behind me was caught completely off-guard and I'm sure wondered what happened. Fortunately there was enough room so she could stop, but it was close.
As new owner, this caught me completely by surprise. This is definitely a brake operation defect and needs to be addressed. Owners need to be aware of this peculiar brake behavior... or the possibility of this happening. When your foot pressure is released, the car MUST respond and the physical brake MUST let go; only regenerative braking is ok. I was very lucky not to have caused a rear end accident to my car. I was very shaken up as I have never had a vehicle respond like this while braking. I'm not bothered by ABS if it lets go when braking pressure is released, but pumping the brake CANNOT cause the car to come to a near stop after foot pressure or your foot is completely removed from the brake peddle.

Yes. I have had my 2011 for almost 18 months, and never had a problem until two weeks ago, when I had a situation nearly identical to what you describe. The only saving grace was no one was behind me. If you look back in this thread, there is a post or two that claims this behavior is "normal", and that if you want the braking to stop, you have to take your foot off the brake *and* press the "go" pedal. Not intuitive at all! I have been meaning to contact Nissan about this, as I too was shaken up.

 

[davewill]

... I'm not bothered by ABS if it lets go when braking pressure is released, but pumping the brake CANNOT cause the car to come to a near stop after foot pressure or your foot is completely removed from the brake peddle.

As leafedbehind noted, it's a feature. Apparently, a lot of people "pump" the brake when trying to panic stop, instead of applying steady pressure to the pedal, and this causes otherwise avoidable accidents. The braking system in a lot of new cars now detects when the pedal is pressed suddenly (panic) and overrides the pedal and keeps the brake engaged until the car is almost completely stopped. This probably happened to you because you were taken a bit by surprise and moved your foot to the brake very quickly. It's been complained about a lot, but if it actually decreases accidents, I can live with it.

 

[turbo2ltr]

The only way something can legitimately be called a "Feature" is if it is repeatable. If it's not repeatable, then it's either a bug (shouldn't happen at all) or a bug (isn't happening when it's supposed to).

Has anyone been able to consistently cause this condition?

 

[davewill]

The only way something can legitimately be called a "Feature" is if it is repeatable. If it's not repeatable, then it's either a bug (shouldn't happen at all) or a bug (isn't happening when it's supposed to).

Has anyone been able to consistently cause this condition?

From earlier in the thread:

I talked to my dealer about this back in August. They gave me a loaner to drive while they worked on it for a couple of days. They were able to duplicate the issue with my car, but not with their demo. They suspected the ABS controller, etc. and were ready to start replacing parts until Nissan corporate told them that the action was a normal function of the brake assist and not to replace any parts. Reluctantly, my dealer called to have me return the loaner and pick up my car. They were very appologetic about not being able to fix the issue and suggested that I contact Nissan customer service to elevate the issue and try to get some action. I eventually called customer service in December to elevate this issue and ask how to keep the heater from coming on while still having forced ventilation. The representative I talked to worked on these issues for several days and kept calling me with updates. Eventually, she had to tell me the corporate answer that this is a normal function of the brake assist system. Although I have not yet done so, I intend to report it to NHTSA to get it into their database.

Before taking my car to the dealer, I did enough testing in a safe area to make some observations about the brake assist system action. I found that the brake assist system seems to function differently if it becomes engaged at higher speeds (say over 50 or 55 miles/hour) than it does when it becomes engaged at lower speeds. If engaged at lower speeds, the brake assist will release the brakes 1/2 second or so after the driver releases the brake pedal. If engaged at higher speeds, the brake assist will keep the brakes applied until the car comes to a complete stop. I also found that the brakes will release immediately when the accelerator pedal is depressed (even slightly) regardless of the speed at which the brake assist becomes engaged.

Gerry

 

[TomT]

Yep, this has been reported before and appears to be a result of how Nissan programmed (or misprogrammed) the Brake Assist feature.

I am new owner of a 2012 leaf. I love the car.
But this morning I had a really scary experience with braking. I was traveling around 25 mph and looked down a moment. Looking up, I noticed the car a ways in front had slowed down a bit, I pumped the brake to equalize the speed, my touch was a bit harder than intended, but I expected the car to quickly drop about 4-5 mph. I got a real scare and scared the ---- out of the car behind when the brakes locked and this rubbing rubber sound emanated. My foot pressure was minimal, but still on the

 

[turbo2ltr]

I was able to incite this "feature", though it was not nearly as drastic as people explained here and definitely did not last until the car stopped. Doing around 40 I quickly stabbed the brakes and let off. When I let go the car continued to slow down (accompanied by a sound that resembled anti-lock brake activation) for maybe 1/2 to 3/4 of a second after releasing the pedal. The deceleration rate was less than when I hit the pedal. When the event was over I was still doing 20 mph (didn't touch the throttle in that time). Now if there is a bug that causes this to happen outside of stabbing the brakes hard, then it would probably be a bit more jarring to the driver.

I was not able to incite this "feature" when I tried several times at higher speeds (over 50)

 

[TomT]

I believe the issue occurs when someone reduces pressure after a panic stop, to modulate the rate of the stop, but does not remove their foot from the brake, at which point Brake Assist continues to be applied and full braking occurs. Anyone who has been trained in proper braking technique will, in fact, never completely remove their foot from the brake...

I was able to incite this "feature", though it was not nearly as drastic as people explained here and definitely did not last until the car stopped.

 

[garygid]

Today the car's automatic panic-stop happened to me.

It almost caused the car behind me to crash into
the rear end of my LEAF, because of the excessive
auto-braking "feature".

After I had removed my foot from the brake pedal, the
car continued to brake abruptly to almost a stop, very
nearly causing an accident as the driver behind me
was also surprised by my car coming almost to a
complete, but unnecessary, stop.

Has there been a resolution to this "feature", or do I
need to report this "feature" to the feds as a safety
hazard? Apparently Nissan refuses to recognize the
safety issue, and says that it is an intended "feature".

I feel that the car MUST stop braking when I take
my foot completely off the brake pedal.

I should also inform Nissan that I consider them liable
for any damages or injuries caused by their overly-extended
duration automatic panic-braking "feature".

 

[cwerdna]

^^^
If you believe it's a legitimate safety defect, I'd file a safety complaint at http://safercar.gov/" onclick="window.open(this.href);return false;

 

[TimLee]

or do I
need to report this "feature" to the feds as a safety
hazard?

I think all drivers need to report what they consider to be a hazard.
I haven't encountered the severe braking "feature" yet (fortunately) in >13,000 miles.
But I detest the built in creep that does nothing but add hazard.
And all the vehicles that now have significant regenerative braking the moment you take your foot off the accelerator and fail to light the brake lights need to be corrected.
I plan to write NTSB on both, but haven't put pen to paper yet.

 

[cwerdna]

or do I
need to report this "feature" to the feds as a safety
hazard?

I think all drivers need to report what they consider to be a hazard.
I haven't encountered the severe braking "feature" yet (fortunately) in >13,000 miles.
But I detest the built in creep that does nothing but add hazard.
...
I plan to write NTSB on both, but haven't put pen to paper yet.

Do you mean NHTSA?

Re: built in creep, see below from http://techno-fandom.org/~hobbit/cars/prius-linkfarm.html" onclick="window.open(this.href);return false;.

http://edocket.access.gpo.gov/2003/03-12051.htm
NHTSA/DOT starter interlock and transmission safety standards NPRM for hybrids, that explains the whole rationale about "creep" force and directional cueing for a driver.

 

[TimLee]

I think all drivers need to report what they consider to be a hazard.
I haven't encountered the severe braking "feature" yet (fortunately) in >13,000 miles.
But I detest the built in creep that does nothing but add hazard.
...
I plan to write NTSB on both, but haven't put pen to paper yet.

Do you mean NHTSA?

Re: built in creep, see below from http://techno-fandom.org/~hobbit/cars/prius-linkfarm.html" onclick="window.open(this.href);return false;.

http://edocket.access.gpo.gov/2003/03-12051.htm
NHTSA/DOT starter interlock and transmission safety standards NPRM for hybrids, that explains the whole rationale about "creep" force and directional cueing for a driver.

Yes, NHTSA.
Interesting reference.
It does help explain why they deemed creep in reverse was considered desirable.
But none of that provides a good explanation for why in the world you would want to include it in forward.
In a very silent electric vehicle, it is very easy to make a human performance error of leaving it in Drive.
The forward creep just creates hazard in this situation, or in drive throughs, or drive through car washes, or congested stop and go traffic.
Nissan should do the right thing like Tesla did and give the driver the ability to turn the forward creep off.

 

[TomT]

Maybe it is all my years of driving manual transmissions, but I hate creep, period. Interestingly, our last BMW 3 series was an automatic and it had virtually no creep. It also would not roll backwards on a hill when you took your foot off the brake.

 

[LEAFfan]

IMO, drivers need to learn to keep a reasonable distance from the car ahead. If the car ahead slams on their brakes for ANY reason, and they are rear-ended, which driver do you think will be cited? It's called NACD (Non-assured Clear Distance). The front driver can be cited also if they hit the car in front of them due to being rear-ended.

 

[OldQuadDog]

While I try to maintain sufficient separation there can be instances when that changes quickly and radically such as another vehicle changes lanes abruptly into my lane and without signalling. The separation distance is immediately compromised. That is what just happened this AM on an expressway at 65-70 mph. My leaf violently decelerated to about 20 mph before the brakes released. The car behind me expressed their disapproval after they had a panic stop to avoid hitting me.

I have just been testing the phenomenon and I can duplicate brake lock-up at will anywhere from 35 mph to 70 mph. All I have to do is punch the brake peddle and immediately release it! The system locks and there is extreme deceleration down to about 20 mph. Obviously not a proper or recommended braking technique but it is how I can duplicate the effect easily and repeatably.

I am on the phone with Nissan service now.
2012 SL 28,500 miles

 

[Ockendonleaf]

i have a uk 2011 leaf which also has this problem what did nissan do about it for you

 

[GerryAZ]

As far as I know, Nissan North America still claims this brake assist action is normal. I don't want to flat-spot the tires on the 2015 so I have not attempted to test this feature on the new one yet. As I noted in an earlier post, be prepared to touch the accelerator pedal after hard braking if you need the brakes to release immediately.

For what it is worth, I only had it happen once with the 2011 in real world driving. Under test conditions on an empty road or track, I could make it happen almost every time I tried by moving my foot very quickly from the accelerator to the brake. There was no difference if I completely removed my foot from the brake or tried to modulate the pressure--I was just along for the panic stop initiated by the car.

Gerry

 

[jpadc]

Since this old thread has been revived, it got me thinking. Lets starting with the fact that I live in flat Indiana and part-time in equally flat Wisconsin, so when I read this post:

http://www.mynissanleaf.com/viewtopic.php?f=27&t=20602#p438792

it came as news to me that the LEAF I’ve been driving for awhile now does have a very cool angle (grade) sensor as part of the braking system. Try it. Come to a complete stop on a relatively steep grade and then take your foot off the brake. Indeed if you stop the car fully on a hill, the car does hold the break on without your foot on the peddle for about 2 seconds (if you don’t press the accelerator). I’m wondering if this is what the OP (and others here) have been experiencing. What’s described in this thread is way more than your average “grabby brake issue” that many of us have experienced at some point (but I don’t anymore for some reason), but maybe a hard press on the brake can inadvertently trip the angle sensor (likely a malfunctioning one) in the car and so you get this couple of second holding on of the brake as

My leaf violently decelerated to about 20 mph before the brakes released

noted. The sensor clearly can malfunction as mentioned in the other thread. Just some early AM wild speculation.

 

[EVDRIVER]

As far as I know, Nissan North America still claims this brake assist action is normal. I don't want to flat-spot the tires on the 2015 so I have not attempted to test this feature on the new one yet. As I noted in an earlier post, be prepared to touch the accelerator pedal after hard braking if you need the brakes to release immediately.

For what it is worth, I only had it happen once with the 2011 in real world driving. Under test conditions on an empty road or track, I could make it happen almost every time I tried by moving my foot very quickly from the accelerator to the brake. There was no difference if I completely removed my foot from the brake or tried to modulate the pressure--I was just along for the panic stop initiated by the car.

Gerry

Flat spot your tires?