Grabby Brakes?

[sunganon]

I think I may have found the solution...

Replace your 12v battery (the "regular" car battery in the front engine bay).

I had the same issues as people described in the numerous posts here. I would characterize it a bit differently however. To me, it felt like whenever I brake, the regen braking would kick on and off. This would cause moderate to severe jerking of the car when coming to a stop. I tried all the solutions posted here with little success (turn off traction control, release braking, etc., update software). The issue would always return.

Desperate for a solution, I took it to the dealership AGAIN and explained what was happening (for the fourth time, now out of warranty). This time the only "code" to show up was for an old low voltage fault of the 12v battery. Luckily, the dealership tech I got this time had seen this issue before, and as weird as it sounds, told me that the 12v battery effects the brake controller. I have a 2012 Leaf, so around 4 years is about how long a car battery lasts in normal cars.

Since replacing the battery (you can do it yourself for around $100) I have not seen this issue return. Hope this helps.

[mikec5537]

The 12V battery is well worth a try. My Prius did some weird things when it went after changing it everything was back to normal. I'll put one on the Leaf at the weekend and let you know....

[goodtimessd]

I just resolved my grabby brake issue, which was becoming borderline dangerous in stop and go traffic. When taking it for service, they addressed a brake related recall, however when reading up on the recall it appears its not specifically for grabby brakes (Recall Number: 16V119000). I read on here about replacing the 12v battery as being a resolution and I did that as well. No more grabby brakes after receiving these two services. I think the 12v battery replacement was what did it, as I've also observed my car not starting (T/M System Malfunction Error) which was due to failing 12v battery. Lesson learned, make sure 12v battery is healthy as this affects more than just powering basic accessories. It's been such a relieve, now that I don't have to deal with annoying grabby brakes anymore.

[rawhog]

Can someone post all of the steps needed when replacing the 12V battery please?

[twood2k]

2012 leaf with hosed battery at 7 bars.

Just adding how i solved the grabbing/releasing brakes in cold weather and low to no regen...
check your front brake pads!I started noticing what i considered dangerous braking where pressing the brakes would result in a sudden release of braking as if i let off of the brake pedal. This would sometimes lead to a sudden grab of the brakes as i tried to compensate...
so it would be this crazy brake no brake situation where i could not have a smooth braking.

I checked the battery and gave it a good three hour 10 amp charge, nothing changed!
I checked my front brake pads and saw about half the pad was there so i decided to replace the front pads with ceramic type pads.
So far i have not experienced the crazy braking!
I do feel the computer ease up on braking sometimes but nothing like the catastrophic feeling i had before.
so im guessing the TSB fixes some aspect of braking but there still is a oversight for brake pad wear and cold weather/ low regen.

just my two cents and i hope this helps.

[Transtead]

I find it interesting that these "normal" ICE vehicle problems are hidden by our car.

In an ICE vehicle, if your battery dies, you can't start it. So there are early signs of "low battery" or even a battery level indicator. In an EV, this is hidden, because only periphery systems use an "external" battery - and probably for redundancy.

In an ICE vehicle, your brake pads wear much faster, and you can feel your breaks "go out" well before. In an EV, the regenerative braking can do most of the breaking so you don't really "feel" it until your car shifts over to manual breaking.

My 2012 is starting to feel it's age - but I still love it.

I wish there were more EV mechanics out there, though. I don't want to take it to the dealership, because they don't care about my EV too much - they don't make money on us.

[Nubo]

I find it interesting that these "normal" ICE vehicle problems are hidden by our car.

In an ICE vehicle, if your battery dies, you can't start it. So there are early signs of "low battery" or even a battery level indicator. In an EV, this is hidden...

Very true and it's unfortunate because a self-diagnostic function could easily and cheaply be built in to the vehicle. Useful and inexpensive digital battery-testers can check not just voltage but capacity as well. EVs would do well to build such circuitry into the car so that the owner can be alerted to a weakening 12V battery before it progresses to where other subsystems are affected. It boggles my mind that this isn't done as a matter of course.

[nlspace]

i've had some grabby brakes that i feel are caused by the response time of the electric motor in the master cylinder. Never had anything like this on any car (ICE or EV) with a vacuum brake booster.

On an old 2012 down to 8 cap bars there is little to no regen braking. If you let off the throttle to coast toward a redlight, then need to add a little braking to slow, then on the second application of the brakes it will nearly lock the car up to a stop with just the slightest of foot pressure on the pedal.

[Nubo]

i've had some grabby brakes that i feel are caused by the response time of the electric motor in the master cylinder. Never had anything like this on any car (ICE or EV) with a vacuum brake booster.

On an old 2012 down to 8 cap bars there is little to no regen braking. If you let off the throttle to coast toward a redlight, then need to add a little braking to slow, then on the second application of the brakes it will nearly lock the car up to a stop with just the slightest of foot pressure on the pedal.

Have you tried the "recalibration procedure"?

[kicker]

I have grabby brakes in the Leaf I have just bought, creeping along in traffic in eco mode seems to show it at its worst.
I'll try a few things independently and see what I find; traction control off and brake depress for 30 seconds, 12v battery check/replace, brake pad and fluid check/replace.