oscar
Posts: 36
Joined: Fri Nov 30, 2012 12:23 am
Delivery Date: 30 Apr 2011
Leaf Number: 000936
Location: San Jose

My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 12:48 am

It happens to my wife once but I didn't believe her last month. I've ask her what happen and describe in sequences. She told me had her foot on brake, press start then put it in Reverse while the foot still on the brake from the beginning. Once in Reverse she looks back and saw people coming so she kept her foot on the brake. All of sudden the brake just felt soft and sink to the floor and car roll. She panic and lift her foot half way off the brake and press again it still roll; while the parents walking in back screaming. My wife pulls the electronic brake it didn’t work. Finally she lifts her foot of the brake completely. Somehow the software figures out the reference point and she hit the brake and it stop. The parent came screaming at her trying killing her kid. After that experience she didn’t borrow my car anymore. So I just brush it off but pay attention to my Leaf thinking she must have done something wrong. Last night first time experience her same symptom. I had my foot on the brake press Start Button then put the car in Reverse and the car roll while my foot is still on the brake. The brake just sinks straight to the floor. I quickly lift my foot completely off the brake and slam on it and it stop. I fear one day someone going kill somebody while the car in Reverse driving a Leaf. I fear during the start the brake lost it reference and software doesn’t know where the reference point begin.


Other Problem!
-Car park on uneven pavement car brake lock! Therefore when you press brake your car can’t start. It can’t register my foot on the brake. (Solution I observe pulls my emergency parking brake on; wait then foot brake release. Turn off the screen now press your foot brake and feel it depress car register your foot on brake then it let you start. Nissan need fix software if roll and lock on an uneven pavement. Lock the brake fine but activate the parking brake then release the foot brake that lock. User now press brake again then start..problem fix! If Nissan not paying to this issue not many Leaf owners will pull their parking brake therefore the system kept saying press brake to start. The only way to release this brake pedal lock you have to activate the parking brake manually. Nissan software should do this automatic!
Otherwise this car is awesome! I’m not sure how long they are keeping my car but once I get it back I will do my best to update everyone in the forum. I just feel my duties to report for safety of Leaf owner to get this fix and enjoyable for future Leaf buyer!

12/01/2012

Ok got the call today to pick up my car tomorrow. Their explanation was I got all these faulty errors was due to a 12V battery. They have all my error codes download and conclude the 12V cause the can bus to go hay wire. They replaced the 12V battery and drain my main battery and recharge. They said everything is working fine. I’ve ask them over the phone was there any cause from the mechanical brake. Their respond was 12V cause faulty error and no mechanical brake issue.

Also the 12V will solve the start issue on the uneven pavement. Guys don’t worry once I get my car back I know where to park to see if this problem is resolve.

For the record before I brought my car in for service. I did check the 12V battery every time I had issues in past. I measure with my voltmeter reading 10.7V to 11.2V.

Anyway I will continue to monitor my issues and update in 3 months. If I see no more issues; I can conclude the 12V battery replacement fix all my issues. I will also ask if they updated the software or kept the current version.

Again Thanks to all that supported my issues and wanting Nissan to improve for future generation to enjoy the Leaf and safety come first!

12/02/2012
Pick up the car this morning. Once started the Leaf mileage reading show 105 miles on display. I’ve notice the brake felt different in a way that it felt stronger not relax feel as before. I drove the car home and measure the voltage and new battery reading 12.31 volts. Anyway I will do more testing on uneven pavement testing in next few days. Hope all my problem is resolve due to low 12V battery. If this is case we should all measure our 12V battery often….wow! Now I’m wondering what happen in real situation when the car let you start up and while driving the 12Volts battery is lost…does this mean you lost power to certain controls? I just hope we don’t lost power to our emergency brake…:)

"Report came back found multiple codes 62 total. The mechanic in charge called the Nissan Tech Line and had them review all but found all up to date. Tech Line confirms that 12V battery went low; recommendations from tech line replace new 12V battery (NB51R). Test drove and check for codes again. All to be ok".

12/03/2012

ok measure with another voltmeter at work. The new reading is 12.47volts. This battery is brand new; replacement just 2 days ago.

Also had a chance to park at 3 different locations on uneven pavement. I couldn't repeat the brake lock symptom anymore.

So I'm going to conclude all my problems that I have listed is due to the 12Volts battery running low in range of 10.7 to 11.3 volts. I hope in near future someone post issues relating to car error. Ask them check the 12volts battery.

Also I agree with one of the post that Nissan should send an email or letter or warning that our 12volts is below the requirement level. I though Nissan download our car information when we hit agreement for information download or I'm mistaking that information download each time we start the car is tracking milage?

Anyway if Nissan can manage to measure the 12volts an display "Warning 12 volts battery replacement or check". It can save lots of headache for future Nissan Leaf owner!
==============>
After thinking with all the pain I had to put up with in past few months. I realize get rid of the tree display and offer me a display to monitor the 12 Volts battery level!!!!!!!!!

We all agree the 12volts battery is the main component in the EV car( I consider the 12volts is a Heart like human body; Heart stop brain won't function anyway)! If 12volts low or dead many of the operation will be non functional! Can someone let Nissan know give us a 12volts display scale! Otherwise future Leaf owner got go buy a voltmeter. When Nissan can display it on the screen.

VIN #000936
Milage:23,700
Last edited by oscar on Mon Dec 03, 2012 5:50 pm, edited 10 times in total.

User avatar
ebill3
Posts: 1400
Joined: Fri May 27, 2011 1:23 pm
Delivery Date: 15 Sep 2011
Leaf Number: 7964
Location: Puyallup WA

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 1:17 am

Well, that seems to be something not previously reported. Good that no one was injured.

Trust you have arranged to have a Nissan shop look into those unusual happenings.
All electric - red LEAF, green Tesla S. No ICE.

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RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 2:57 am

That's pretty scary! It's good no one was hurt or killed.

There is new firmware available for the braking system in the LEAF which addresses the brakes being grabby. I wonder if it also addresses this issue.

In any case, I would definitely get the car in to your Nissan dealer as soon as possible.
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

vegastar
Posts: 208
Joined: Mon Dec 13, 2010 11:29 am
Delivery Date: 07 Jul 2011
Leaf Number: 5564
Location: Portugal

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 3:30 am

I tought the pedal connection to the brakes was mechanical with hydraulic assist. With that in mind it is strange that flooring the brake wasn't enough to stop the car.
2011 Nissan LEAF since 2011-07-07, 151000 km on 2018-03-03, 7 bars, 37.9Ah.

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RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 5:05 am

vegastar wrote:I tought the pedal connection to the brakes was mechanical with hydraulic assist. With that in mind it is strange that flooring the brake wasn't enough to stop the car.
That was my first thought, as well. But after thinking about it further, the brakes on the LEAF are assisted by an electric pump, so it seems possible that a failure to start the assist pump motor might result in such a fault. Perhaps fluid can flow backwards through the pump if it is not running.

In any case, the assist does not come directly from the running engine as it does in a conventional ICE, so it is certainly possible to have the car drivable but the brake assist off.

I have no idea why the parking brake was also not working. Perhaps the ultracapacitor got into a discharged state somehow?
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

Smidge204
Posts: 940
Joined: Wed Nov 24, 2010 1:42 pm

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 6:27 am

The LEAF uses a fairly standard hydraulic braking system just like any other car, with the main difference being that the brake boost is done via electromagnetic coils instead of a vacuum and diaphragm (because there's no engine intake manifold to provide a vacuum). The strength of the boost is what gets controlled to balance regen and friction braking.

If the boost system fails you should still have brakes, but you would have to push very hard on the pedal to get strong braking force - they will feel very stiff, not soft. Under no circumstances should the pedal go all the way to the floor. This is a serious mechanical malfunction of the braking system and you should have it looked at immediately if not sooner. I guarantee this has nothing to do with firmware.

My two cents. Also, the electric parking brake should have more than enough schlitz to stop the car, especially if you pull it twice to "double engage" it. The capacitor has nothing to do with the parking brake AFAIK. It's there to maintain the ABS and hydraulic boost systems.

Edit: reading the service manual more carefully, there appears to be a small, physical gap between the pin attached to the brake pedal and the master cylinder internals. It's the movement of the pedal within this gap that allows regen with no friction braking at all... but that's irrelevant here since the pedal was fully depressed. You should have full mechanical braking at that point, and the fact that it still failed means it's a mechanical failure.
=Smidge=

69800
Posts: 173
Joined: Fri Dec 30, 2011 2:21 pm
Delivery Date: 03 Jan 2012
Leaf Number: 16583
Location: North Idaho

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 7:31 am

If the boost system fails you should still have brakes, but you would have to push very hard on the pedal to get strong braking force - they will feel very stiff, not soft. Under no circumstances should the pedal go all the way to the floor. This is a serious mechanical malfunction of the braking system and you should have it looked at immediately if not sooner. I guarantee this has nothing to do with firmware.

I agree with Smidge. This is a mechanical problem and needs to be looked at NOW.

Now that we are aware that it can happen we should all be ready to push the park button in an emergency like this.

I also have warned my wife that if the power steering fails....The steering is probably going to feel like its locked...but to hang on and use lots of muscle. It could catch you off guard in a corner
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RegGuheert
Posts: 6419
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 8:06 am

Smidge204 wrote:Also, the electric parking brake should have more than enough schlitz to stop the car, especially if you pull it twice to "double engage" it. The capacitor has nothing to do with the parking brake AFAIK. It's there to maintain the ABS and hydraulic boost systems.
O.K. Agreed that it looks like the ultracapacitor does not provide backup power to the parking brake. IMO, this is a major defect in the system design since loss of 12V power means loss of the parking (emergency) brake. Perhaps this is one reason they chose to move back to a mechanical brake in 2013. It IS mechanical for 2013, is it not?

In this case, maybe the issue was simply that the emergency brake was too slow to provide help in stopping the car in time. OTOH, it appears there were serious problems going on, so perhaps power was lost to the emergency brake system.
69800 wrote:Now that we are aware that it can happen we should all be ready to push the park button in an emergency like this.
Yes, I was starting to think about what to do in this case and shifting to park came to mind. Does anyone know the maximum speed at which the parking pawl will move into the locked position?
RegGuheert
2011 Leaf SL Demo vehicle
10K mi. on 041413; 20K mi. (55.7Ah) on 080714; 30K mi. (52.0Ah) on 123015; 40K mi. (49.8Ah) on 020817; 50K mi. (47.2Ah) on 120717; 60K mi. (43.66Ah) on 091918.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

DaveinOlyWA
Posts: 15163
Joined: Sat Apr 24, 2010 7:43 pm
Delivery Date: 16 Nov 2019
Leaf Number: 319862
Location: Olympia, WA
Contact: Website

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 8:14 am

when i first read your post, i was horrified that this scenario was even possible.

I have spent quite a while in my driveway (very steep) trying to reproduce this and have failed.

my driveway is so steep that in Eco, it will roll backwards if there is no foot on Accelerator or brake. in every instance, it was very easy to stop the car (i do it several times a day now. i live on street that is one block long and there are kids playing on it ALL the time)

have to guess your wife was simply not pushing on the brakes very hard. I was able to get the brakes to lose their sponginess and it does seem like you need to push somewhat harder to brake??

during this trial, i also noticed a very slight change in my mechanics. unlike forward momentum which pushes you into the brake direction when slowing, reverse pulls you away from it and there was a few times i had to be diligent about simply not pushing "harder" but pushing "farther"

i will say one thing. i am at 1.8 miles/kwh after .3 miles of driving...not a good start to the day!

either way, i think you should try to reproduce this. if you cant? well...but there is always the possibility of a defect no matter what anyone tells you here. we can only relate our experiences with our cars. keep in mind; i have ZERO experience with yours
2011 SL; 44,598 mi, 87% SOH. 2013 S; 44,840 mi, 91% SOH. 2016 S30; 29,413 mi, 99% SOH. 2018 S; 25,185 mi, SOH 92.23%. 2019 S Plus; 14,342.8 mi, 93.16% SOH
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smkettner
Posts: 7501
Joined: Mon Aug 09, 2010 10:13 pm
Delivery Date: 26 Feb 2014
Location: Orange County, CA

Re: My Leaf roll back and almost kill a kid!

Fri Nov 30, 2012 9:23 am

I would take it in and get a new master cylinder installed along with full flush of the fluid. Unless Nissan can duplicate the issue and it is known to be something else. This should be under warranty.

The parking brake does take a couple seconds to engage.... and could seem like an eternity during a panic. In all the confusion I think this may have been what stopped the car.
1 bar lost at 21,451 miles, 16 months.
2 bar lost at 35,339 miles, 25 months.
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RAV4 traded in for I-Pace Dec 2018

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