Grabby Brakes?

[GeekEV]

I haven't seen the grabby brake syndrome discussed in a while, what with all the battery talk going on. Mine is getting steadily worse and is happening more and more often. I've tried to pay attention and establish a repeatable pattern, but can't. I'm tempted to take it in to the dealer and just tell them to ride around with me for a while until it happens. Has anyone managed to recreate it on demand yet?

 

[LeafLiam]

I noticed this a few times. It felt like the regen wasn't happening and the calipers were freaking out. On both occasions I pulled over and powered down the Leaf and then started again ( like a computer re-boot) and this solved the problem.

 

[ericsf]

It's been several months for me without a single occurence of the "grabby brakes" syndrom. The only maintenance I did was to wash the car and replace the windshield wiper blades. As far as I can tell. it went away by itself. I'm due for my 30K in a month or so. The dealer will probably push me the brake fluid replacement. It will be interesting to see if it brings it back.

 

[DeaneG]

After 14.5K miles I still get grabby brakes every day or two. Often it happens when I apply the brakes at low speed, let off again somewhat, and gently re-apply, like when moving around in a parking lot. Letting fully off the brakes briefly always cures the problem until the next time it happens.

 

[jspearman]

We've had the grabby brake thing when creeping forward and applying the brake. Scares the bejeezus out of my wife every time it happens. Also had an even stranger brake thing happen yesterday. Shut the car off outside the garage, walked in for about thirty seconds, started it up again and was creeping into the garage and nearly hit my other car because the brakes seemed to fail until I put my foot nearly to the floor. Next morning, no problem.

 

[gfederas]

After 14.5K miles I still get grabby brakes every day or two. Often it happens when I apply the brakes at low speed, let off again somewhat, and gently re-apply, like when moving around in a parking lot. Letting fully off the brakes briefly always cures the problem until the next time it happens.

I have had the same experience as DeaneG with the same solution.

 

[derekjsmith]

After 14.5K miles I still get grabby brakes every day or two. Often it happens when I apply the brakes at low speed, let off again somewhat, and gently re-apply, like when moving around in a parking lot. Letting fully off the brakes briefly always cures the problem until the next time it happens.

I have had the same experience as DeaneG with the same solution.

Same here after 18k miles. But I can repo at higher speeds as well. Has nothing to do with regen this happens in D/Eco/N. But my driving style and background is different than most as a professional driver and high performance “racecar” driving instructor. My learned braking technique is you go quickly and firmly but not aggressively to brakes and release pressure or modulate as needed but never full release until stopped. In doing so the algorithms for the assisted collision avoidance system gets confused and thinks I really meant to do a panic stopped but did not activate the ABS so it will boost the applied ratio. And yes by fully releasing the brakes for a second or so it resets the algorithm and you are back to normal.

 

[GeekEV]

FYI, I just got the following message from my dealer this morning:

Nissan has a brake control unit update out for the sensitive brake feel issue. It just came out this morning. You can schedule a time to bring it in. It should take about an hour to do the actual update plus time to get it through the shop. Call XXX for an appointment at XXX-XXX-XXXX or let me know and I can set something up.

Thanks

XXX XXX

I'll try to find out the TSB number and post it up when I get it.

 

[GeekEV]

More info:

It is NTB12086. It says the customer states the brake pedal feels more sensitive at speeds below 15 MPH. We have to go in and check the current part version number of the brake control and see if the update applies. The TSB is for 2011 LEAF, they say it’s for vehicles built after a certain VIN but I think that must be a mistake. Either way we can check your brake control unit for an available update.

 

[lemketron]

After 14.5K miles I still get grabby brakes every day or two. Often it happens when I apply the brakes at low speed, let off again somewhat, and gently re-apply, like when moving around in a parking lot. Letting fully off the brakes briefly always cures the problem until the next time it happens.

I have had the same experience as DeaneG with the same solution.

Same here after 18k miles. But I can repo at higher speeds as well. Has nothing to do with regen this happens in D/Eco/N. But my driving style and background is different than most as a professional driver and high performance “racecar” driving instructor. My learned braking technique is you go quickly and firmly but not aggressively to brakes and release pressure or modulate as needed but never full release until stopped. In doing so the algorithms for the assisted collision avoidance system gets confused and thinks I really meant to do a panic stopped but did not activate the ABS so it will boost the applied ratio. And yes by fully releasing the brakes for a second or so it resets the algorithm and you are back to normal.

I had a similar experience recently, where I believe the ABS was activated for me, and releasing the brakes didn't seem to help:

I was driving along and noticed that the car in front of me had come to a rather quick stop. I could have stopped fast myself and would've been fine, but I feared getting rear-ended. Instead, I decided to tap my brakes repeatedly a few times to flash my brake lights to make sure the guy behind me knows that I need to stop. I did NOT plan to stop immediately but rather in a very controlled stop over the distance that I still had in front of me.

I did this by tapping the brakes to flash the lights, intending to then apply whatever pressure I needed to stop. What happened instead is that after I tapped the brakes a few times, the LEAF seemed to get confused and applied the brakes hard, which then locked up the wheels and subsequently (appeared to) activate the ABS to stop the car rather than letting it skid on down the road. That was annoying but it shouldn't have been a big deal. I instantly removed my foot from the brake pedal, which in any other car would let go of the brakes so I could decide to pump them again, or not. However, the LEAF didn't kill the ABS. Instead it continued to bring the car to a very fast stop. That would have been great, if that's what I had wanted, but it wasn't. It sounds like what derekjsmith noted above:

...the algorithms for the assisted collision avoidance system gets confused and thinks I really meant to do a panic stopped but did not activate the ABS so it will boost the applied ratio...

Instead of simply warning the guy coming up fast behind me that I was slowing down (and then slowing down slowly), I basically stopped right in front of him, forcing him to do the same. He actually swerved to the right (which could've caused other problems since there were other cars approaching in the next lane) and fortunately was able to stop without hitting me, though when I realized what was happening I was sure he was going to rear-end my LEAF. It really freaked me out since I had removed my foot from the brake, but the car did not release the brakes until after I had come to a complete stop (which nearly resulted in having a pickup truck in my rear seat).

The good news is nobody hit anybody, but a few of us got really frazzled... and I often wonder in a situation like this if there wasn't some sort of chain-reaction several cars back where someone might have hit someone else without our even realizing it...

 

[garygid]

Really, there are two different, probably related problems.

1. The grabby brakes until one releases the brake pedal completely.

2. The ABS kicking in, and abruptly stopping the car, even wheny
the foot has been removed from the brake pedal.

This second problem is much more life-threatening!

Does Nissan even admit that the second problem exists?

Perhaps activating the go-faster pedal would release the ABS?

Does this firmware update fix BOTH of these problems?

 

[DaveEV]

Perhaps activating the go-faster pedal would release the ABS?

This likely would have released ABS if releasing the brake pedal didn't.

I'm really not a fan of Brake Assist.

And yes - none of this is likely to be related to the grabby-brake syndrome as Gary suggests given the low speeds when grabby-brake syndrome appears.

 

[DeaneG]

I just had the software update applied to my Leaf at Sunnyvale Nissan. Even though it was the first time they'd applied the fix, they completed the operation including a car wash in less than an hour. They were very happy to learn of this solution to a common customer complaint.

It may be a figment of my imagination, but the brake pedal feel at low speeds seems to be improved (firmer and more connected) compared to the previous release, even when the "grab" wasn't occurring.

 

[bowthom]

I got caught in creeping traffic on the freeway where I was applying a small amount of brake controlling the car's "creep" speed. The brakes were constantly grabby the whole time because we never got to a speed where I could fully release the brakes. It became very annoying after 45 minutes of it.

I'm taking mine in at first opportunity.

 

[GeekEV]

The brakes were constantly grabby the whole time because we never got to a speed where I could fully release the brakes. It became very annoying after 45 minutes of it.

FWIW, I had found that even under these circumstances, you can *very quickly* take your foot off and immediately slam it back down to reset. Sure, you jerk and lurch, but you were doing that anyway. :lol:

 

[GerryAZ]

Really, there are two different, probably related problems.

1. The grabby brakes until one releases the brake pedal completely.

2. The ABS kicking in, and abruptly stopping the car, even wheny
the foot has been removed from the brake pedal.

This second problem is much more life-threatening!

Does Nissan even admit that the second problem exists?

Perhaps activating the go-faster pedal would release the ABS?

Does this firmware update fix BOTH of these problems?

I cannot find it right now, but there is another thread dealing with brake assist. I did some testing in a safe area and confirmed that pressing the accelerator will release the brakes. I took my LEAF to my dealer and complained. They were able to duplicate the issue and were ready to start replacing parts before Nissan told them it is normal and directed them to not do anything. Bottom line: Be prepared to move your foot quickly to the accelerator to get the brakes to release. I personally will never buy another car with "brake assist", no matter which manufacturer because I consider this to be a major safety concern.

Gerry

 

[GeekEV]

2. The ABS kicking in, and abruptly stopping the car, even wheny
the foot has been removed from the brake pedal.

This second problem is much more life-threatening!

Does Nissan even admit that the second problem exists?

I cannot find it right now, but there is another thread dealing with brake assist. I did some testing in a safe area and confirmed that pressing the accelerator will release the brakes. I took my LEAF to my dealer and complained. They were able to duplicate the issue and were ready to start replacing parts before Nissan told them it is normal and directed them to not do anything. Bottom line: Be prepared to move your foot quickly to the accelerator to get the brakes to release. I personally will never buy another car with "brake assist", no matter which manufacturer because I consider this to be a major safety concern.

Gary, no Nissan doesn't admit the problem exists - it's been well discussed here (and in their various documentation) that it's a feature done on purpose. As for you and Gerry thinking it's a safety issue, I've tried to engage brake assist on purpose to see it's behavior and haven't been able to (even before the update). So whatever panic stop conditions it's designed to assist with seems to be accurate enough that I can't make it do it on purpose. Although it sounds like Gerry can.

The rationale for this feature seems to be that a lot of people (especially older drivers) tend to pump the brakes during a panic stop even when with ABS that's not necessary and even detrimental to stopping distance. Hence when they detect such a condition, they're going to save you from yourself and STOP THE CAR NOW. I don't see how it's life threatening, unless it engages when you're not braking at all. Even if it engages inappropriately when you're trying to do a normal stop, the people behind you should also be preparing for your stop. Even if they're not expecting you to stop that quickly (which, ultimately, really, means they're following too close), the worst that would happen is you get rear-ended. How is that life threatening?

But now we risk hijacking this thread from it's original topic...

 

[johnr]

@ GeekEV:
Were you able to see your dealer for that update yet? I'm curious if it solved the grabby brakes problem.

 

[TomT]

Yes it does.

 

[johnr]

Yes it does.

That's good. Now my next question is, How would someone go about getting this update? I for one haven't gotten any official notification that an update for the braking issue is available. If I go to the local dealer and ask to get the brake software updated, I'm not sure they would know what I'm talking about. I hope Nissan makes it an official "recall".