Brakes "mutate" to become grabby in stop & go traffic?

Not that I want to create a problem for myself! But is this how to replicate?

1.find a hill with a slight downhill grade...
2.proceed from top of hill, at a creep, with constant brake applied at low speed.
3.continue until brake feather is not longer available, and until brakes become/are "grabby".

To end experiment, come to complete stop (at side of road). Hold brakes with sustained pressure and movement, and place in park. Fully release brake.

Maybe power cycle car?

Is that it? I have not experienced the "grab" issue, but want to know what it is...

Yeah, I think that's it, more or less. I don't think you need a hill, but it wouldn't hurt.

There might be more to it. I tried to recreate it today on a very mild downhill grade, and could not.

I spent 5-10 minutes with various amounts of brake force, but didn't get any anomalies. I tried level road and mild downhill grade, but not as steep as when I first encountered it.

Hmm..

I tried it on my way home today and, somewhat to my surprise, it actually did cause the problem to disappear. I wonder how long this "cure" will hold...

garygid said:

I will try this "fix" also:
1. LEAF not moving, probably in "D",
2. Turn Traction Control Off
3. Press brake firmly
4. Hold for 30 seconds or so
5. Vary pressure a bit to see if it is spongy or firm
6. ... notice any results!

Click to expand...

That's great TomT, maybe we're onto something.
You made my night!

garygid said:

Are these "annoying" braking characteristics being reported to Nissan (877-664-2738)?

To help Nissan become aware and improve the LEAF, we should be reporting these "unexpected" vehicle control "problems".

Click to expand...

Oddly enough when I called Nissan, they refered me back to the dealer. Even when I told them the dealer thinks the sudden and unexpected stop is "normal operation" for the Leaf. They did point me to the Nissan USA customer comment form. I sent my concerns that way, but I am not sure that they will get to the appropriate people at Nissan.

Has anyone else taken it in have a dealer look at it?

How many have tried the "fix" and did it work or not?

Follow up from the dealer. The service manager says they talked to Nissan "on tech net". I got the impression that it was a system for Nissan to inform techs of trouble, but not necessarily a way for techs to report trouble to Nissan. It took a week for the service manager to call me back after our initial phone call. He is definately backing up his service tech that these grabby brakes are normal behaviour. I'm not sure if I want to go back to this service department or not... Does anyone in the Greater Seattle area have a service department that they love?

FairwoodRed said:

... He is definately backing up his service tech that these grabby brakes are normal behaviour. I'm not sure if I want to go back to this service department or not...

Click to expand...

Given the number of folks that have verified the same behavior, it seems obvious that it is normal for the LEAF. The question really is whether it's acceptable. I've not found it to be dangerous, and having gotten a feel for it, I can usually avoid the circumstances.

Alas, after a couple hundred miles, it reverted to the exact same problem so clearly this is not a long-term solution. I'm still leaning toward a software bug that will ultimately require a patch to fix. It may not be dangerous per se - though an argument could be made about it increasing the possibility of being rear-ended - but I most definitely would not call it satisfactory or "normal."

TomT said:

I tried it on my way home today and, somewhat to my surprise, it actually did cause the problem to disappear. I wonder how long this "cure" will hold...

garygid said:

I will try this "fix" also:
1. LEAF not moving, probably in "D",
2. Turn Traction Control Off
3. Press brake firmly
4. Hold for 30 seconds or so
5. Vary pressure a bit to see if it is spongy or firm
6. ... notice any results!

Click to expand...

Click to expand...

I got stuck late Friday night in stop and go traffic on the 405 Southbound, to Sunset, West Los Angeles. Conversely, I had almost an hour to try and intentionally generate the issue on that downhill incline, and failed to do so. Not that I am complaining or anything...

TomT said:

Alas, after a couple hundred miles, it reverted to the exact same problem so clearly this is not a long-term solution. I'm still leaning toward a software bug that will ultimately require a patch to fix. It may not be dangerous per se - though an argument could be made about it increasing the possibility of being rear-ended - but I most definitely would not call it satisfactory or "normal."

TomT said:

I tried it on my way home today and, somewhat to my surprise, it actually did cause the problem to disappear. I wonder how long this "cure" will hold...

garygid said:

I will try this "fix" also:
1. LEAF not moving, probably in "D",
2. Turn Traction Control Off
3. Press brake firmly
4. Hold for 30 seconds or so
5. Vary pressure a bit to see if it is spongy or firm
6. ... notice any results!

Click to expand...

Click to expand...

Click to expand...

I was in stop-and-go the other night and and I noticed it for the first time. I think it only happened once or twice and then it went away. Personally, I don't like it but if that's just the way they are I'll adjust.

FWIW My Subaru Forester has it's own quirks; When I brake in that car while in gear (it's a manual trans) and then put it in neutral, the RPMs will drop to and idle level, stay there for a second, and then a moment later they'll go up to about 2,000 and then back down. When this happens under steady brake pressure it causes the brake pressure to drop which requires me to push the brake petal further to continue the steady braking pressure. I've been told its normal behavior and after 4 years I hardly notice it any more.

Well, I and the Leaf's brakes nearly caused an accident this morning. I was adjusting the climate control in rush-hour stop-n-go traffic and when I looked up I noticed I was approaching the car in front of me too rapidly, so I quickly put my foot on the brakes. The ABS engaged, and I quickly realized I had over-reacted so I immediately took my foot off the brake pedal, but they insisted on staying engaged, maybe for a second or so longer. My continued rapid deceleration made the guy behind me slam on his brakes (I heard his ABS, too) and luckily no one hit anyone else. But, sheesh! I've had the ABS engage in other cars before, and have never had it "linger' like that after relesing the brakes. Is this considered "normal"?

BTW, I also have experienced the more commonly described grabby brake syndrome.

No, I don't personally think either is "normal." Both certainly do seem like safety issues, all other considerations aside. We can only trust that Nissan is aware of this and working on a software update to address it, and that it will be rolled out to all previous vehicles. I trolled the NHTSA database and there already seem to be a number of entries about it though many of them describe it poorly...

I wonder if other Nissan's have the same issues or if it is isolated to just the Leaf? Back to the database, I suppose.

I can say that none of my other vehicles that have had both ABS and Brake Assist have demonstrated this behavior...

philaphonic said:

Well, I and the Leaf's brakes nearly caused an accident this morning. I was adjusting the climate control in rush-hour stop-n-go traffic and when I looked up I noticed I was approaching the car in front of me too rapidly, so I quickly put my foot on the brakes. The ABS engaged, and I quickly realized I had over-reacted so I immediately took my foot off the brake pedal, but they insisted on staying engaged, maybe for a second or so longer. My continued rapid deceleration made the guy behind me slam on his brakes (I heard his ABS, too) and luckily no one hit anyone else. But, sheesh! I've had the ABS engage in other cars before, and have never had it "linger' like that after releasing the brakes. Is this considered "normal"? BTW, I also have experienced the more commonly described grabby brake syndrome.

Click to expand...

i see this EVERY day coming home from work. i work 11 hour shift so go in very early, come home with everyone in the county. so morning commute; about 11 minutes. afternoon commute; 18-25 minutes.

now, i tend to not move until there is about 2-3 car lengths to coast and i try to time it with the movement. (i can see the light a half mile away. so after it turns green, the cars usually start to move about 90-120 seconds afterward)

but the brake grab feel is always removed when i get up to around 10 mph or so give or take.

i experience the same thing on the Prius but it doesnt have nearly the grabby feel. its mostly a change in the brake pedal feel. there are times when the brake pedal on the Prius will go nearly to the floor

i just write it off as ABS performance. i find it very difficult to be concerned about an issue at 3 mph. but then again, i have never had it happen to me if i was doing any real moving.

what i would do if possible, is wait until you can move farther to move.

i will play with it tomorrow and see if i can detect a "cut- away" speed or something. wondering if it is tied into the "auto door locks" which happen around 7-8 mph or so?

another note; getting rear ended in bumper to bumper traffic?? that is not a brake issue.

TomT said:

We can only trust that Nissan is aware of this and working on a software update to address it

Click to expand...

Please don't trust that Nissan is aware of this. After getting no joy at my dealer, I contacted Consumer Affairs. They've arranged a ride along with me this Saturday, although it is at the same dealer as before. Consumer affairs gave me the impression that they do not see any widespread problem with the brakes, but that they are taking these extra steps to satisfy me personally.

For me this problem is intermittent and "I" can't reproduce it on command. That means that I have small hopes that the dealer will get to see the problem in action this Saturday.

Please, if anyone is having this problem, contact your dealer to get it looked at. Right now, braking troubles are not on Nissan's radar.

Have you tried turning off the traction control temporarily to see if the issue goes away like it did for me? I've seen a slight return of the issue after about 500 miles, but nothing like before.

Has anyone had more luck reproducing this consistently? I've noticed it happening more and more often and at higher speeds these days. Oddly, when it happens at higher speeds it usually only happens for one brake application, the next one is usually fine. I still wouldn't classify it as a safety problem (yet), but it sure is annoying.

FairwoodRed said:

garygid said:

Are these "annoying" braking characteristics being reported to Nissan (877-664-2738)?

To help Nissan become aware and improve the LEAF, we should be reporting these "unexpected" vehicle control "problems".

Click to expand...

Oddly enough when I called Nissan, they refered me back to the dealer. Even when I told them the dealer thinks the sudden and unexpected stop is "normal operation" for the Leaf. They did point me to the Nissan USA customer comment form. I sent my concerns that way, but I am not sure that they will get to the appropriate people at Nissan.

Has anyone else taken it in have a dealer look at it?

How many have tried the "fix" and did it work or not?

Follow up from the dealer. The service manager says they talked to Nissan "on tech net". I got the impression that it was a system for Nissan to inform techs of trouble, but not necessarily a way for techs to report trouble to Nissan. It took a week for the service manager to call me back after our initial phone call. He is definately backing up his service tech that these grabby brakes are normal behaviour. I'm not sure if I want to go back to this service department or not... Does anyone in the Greater Seattle area have a service department that they love?

Click to expand...

I also called Nissan's 877 number and mentioned I had just gotten the firmware update and hoped that would solve the problem, but hasn't. (In fact, right after the firmware update at the dealer, the guy driving the car out noticed it when he stepped on the breaks.) The 877 number people "hadn't heard of the problem" but took a note and gave me a file number. I mentioned that on the boards, lots of people are reporting the exact same issue.

Next step is to call the dealer (at their suggestion) but I suspect I'll get the same "that's the way it is supposed to work" type comment.

The Volt has the opposite problem.. I notice it when going through the base gate especially in the morning. While the brakes are not over reaching on application they usually stick momentarily when my foot comes off the brake for a second or so.... Will be interesting to see the opposite problem happen in the Leaf. When we drove one the 20 miles or so the one day I did not notice anything abnormal. Is this a frequent or rare thing? Seems to me some experience it a lot while others not so much. On the Volt I have noticed there is that regen area at the top, and when I get in to stop & go like the HRBT that it has a weird braking feeling cause you need to push it more to get to the real brakes to actually stop. Sometimes I find myself slowly creeping forward at lights and such before having to mash the pedal further. Is a weird sensation to explain.

Roadburner440 said:

...Is this a frequent or rare thing? Seems to me some experience it a lot while others not so much...

Click to expand...

I think it may be relating to driving style.

If you plan to come to a stop and make one continuous braking action to get to a stop then maybe you don't notice this.
But if you are someone that starts slowing down more ahead of time, lets off of the brake, then pushes it again as you are getting closer to traffic then you may find it grabs sometimes. I find it happens when making lots of little pedal "on / off" efforts in really slow traffic.
It usually only happens to me as I am coming to a stoplight with other cars speeding up and slowing down in front of me.
My usual reaction was "whoa!, I didn't mean to brake THAT hard!" It isn't like skidding, screeching. More like "I stopped cold when I meant to creep forward a bit more."


Somewhere I read this was related to some intentional "brake assist" feature, which is apparently a safety feature to help people avoid accidents in some sort of panic stop situation. Perhaps the "algorithm" is just a little too eager to engage the feature.

Roadburner440 said:

On the Volt I have noticed there is that regen area at the top, and when I get in to stop & go like the HRBT that it has a weird braking feeling cause you need to push it more to get to the real brakes to actually stop. Sometimes I find myself slowly creeping forward at lights and such before having to mash the pedal further. Is a weird sensation to explain.

Click to expand...

common feeling in my Prius as well. it simply feels like there is no brake pedal pressure like your fluid is all running out as you push the pedal down to the floor.