Scary braking problem

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MyAlias

New member
Joined
Aug 11, 2010
Messages
4
Both my wife and I have experienced a rather scary braking problem.

I had to slow down suddenly and I pressed hard on the brakes. I then let up on the brakes, but the car kept braking hard and the tires locked. Fortunately, it skidded straight ahead, but it could have gone much worse.

Clearly there is a delay in the release of the regenerative braking that is normally not a problem, but it becomes a problem when you are trying to do a controlled, hard brake.

Has anyone else experienced this problem? It has us rather nervous.
 
MyAlias said:
Both my wife and I have experienced a rather scary braking problem.

I had to slow down suddenly and I pressed hard on the brakes. I then let up on the brakes, but the car kept braking hard and the tires locked. Fortunately, it skidded straight ahead, but it could have gone much worse.

Clearly there is a delay in the release of the regenerative braking that is normally not a problem, but it becomes a problem when you are trying to do a controlled, hard brake.

Has anyone else experienced this problem? It has us rather nervous.


I've only had to brake hard once when someone cut right in front of me in the carpool lane. My Leaf did a great job, no lockup, and released normally. Since then, I actually feel safer in my car due to the brakes then in my old Civic Hybrid.
 
I agree with the others to take the car to the dealer to have it inspected. It seems the problem is repeatable so it should be fairly easy for them to diagnose. I don't believe it has anything to do with regen. This is my own opinion but regen does not have enough lower to lock up the wheels. You only have 30kw of power and that is just enough to slow the car, not stop it and definitely not enough to lock the wheels and cause a skid. I'd suspect a faulty hydraulic part in the braking system.

I hope they can fix it quickly so you and your wife can regain the confidence in the car that it deserves.
 
This sounds like a problem with the anti-lock brakes, not regeneration. Regen doesn't have enough power to lock up the wheels; only the brake calipers can do that.
 
Did you get an Anti-Lock fault light? Have your dealer check it out.

I have had one emergency stop and it was in a downpour. Amazing braking power and stability. Just about sucked our eyeballs out!
 
rawhog said:
Before filing complaints with government agencies, why not take it to the dealer?

What is the purpose of the safercar.gov thing? To provide a means to escalate safety concerns not resolved by the dealer/mfr or to provide an independent data collection point to gather information about safety concerns people have with particular models?

Just about everyone knows how frustrating it can be to pull up in the service dept and tell them about an intermittent problem. Who knows maybe 5% of Leaf owners are experiencing this problem (not likely given this forum) and individual service departments are shrugging it off since no problem is apparent, and nobody is catching that data.
 
LTLFTcomposite said:
rawhog said:
Before filing complaints with government agencies, why not take it to the dealer?
What is the purpose of the safercar.gov thing? To provide a means to escalate safety concerns not resolved by the dealer/mfr ...
Seems like you answered your own question.
 
I probably should know this (but I don't...), but I know plenty of modern cars, Nissans included, have brake assists that apply the brakes into the ABS when they sense you've been startled and went for the brake (snapping the throttle closed, immediately hitting the brakes hard).

I'll take my demo out and give it a shot and see if I can replicate it.

That being said, take it back to the dealer, and have one of their LEAF techs sit shotgun while you drive, and replicate the issue.
 
LTLFTcomposite said:
rawhog said:
Before filing complaints with government agencies, why not take it to the dealer?

What is the purpose of the safercar.gov thing? To provide a means to escalate safety concerns not resolved by the dealer/mfr or to provide an independent data collection point to gather information about safety concerns people have with particular models?

Just about everyone knows how frustrating it can be to pull up in the service dept and tell them about an intermittent problem. Who knows maybe 5% of Leaf owners are experiencing this problem (not likely given this forum) and individual service departments are shrugging it off since no problem is apparent, and nobody is catching that data.
I think that hits the nail on the head. Regardless of whether or not it's taken to the dealer (and whether or not it's blown off and recorded in a database or not), I think if it is a legitimate safety complaint, you should file it with NHTSA anyway. Even if the issue is properly repaired, if it's a legitimate safety issue, I'd still file a safety complaint and also indicate how it was resolved/the problem found.

Although this is from a Toyota rep, I think Prius Team's reply at http://priuschat.com/forums/prius-hybrid-ev-alt-fuel-news/76158-prius-brake-recall-little-more-information-4.html#post1061546 and http://priuschat.com/forums/prius-hybrid-ev-alt-fuel-news/88347-toyota-unveils-entune-app-ready-sync-fighter-ces.html#post1239131 sum it up pretty well. I have personally met Doug.

Also from http://priuschat.com/forums/prius-hybrid-ev-alt-fuel-news/76158-prius-brake-recall-little-more-information.html, people were complaining about a similar "brake pause" that's a known quirk (something you have to get used to) on 2nd gens, yet no "recall"/firmware update was in the piple to which Doug responded:
Q8. Why are there over 400 complaints registered in the NHTSA data base for braking conditions on a second generation Prius? This seems to indicate the brake recall for the 2010 MY Prius also should apply to the 2004-2009 MY Prius.
A8. Because the ABS system and software is completely different between the second and third generation Prius, we need to evaluate complaints separately. We are willing and eager to evaluate concerns observed on second generation Prius that are similar to A0B on third generation Prius. Please help us identify and remedy any issue by contacting your local dealer. Please keep in mind that posts on PriusChat (a third-party forum) or other similar sites are NOT in any way an official registration of your concern, and cannot help us diagnose the issue.

Anecdotal reports here or reported to the dealer (but blown off and not logged) don't really help. I'm sure Nissan and the government monitor certain channels and automakers have to take action if NHTSA starts an investigation. Sometimes, they lead to recalls.

From https://www-odi.nhtsa.dot.gov/ivoq/index.cfm:
Why your complaint is important

Your complaint information will be entered into NHTSA-ODI's vehicle owner's complaint database and used with other complaints to determine if a safety-related defect trend exists. More...

* If a safety-related defect exists in a motor vehicle or item of motor vehicle equipment, the manufacturer must provide a remedy at no cost to the owner. Your complaint is the first step in the process.
* We do not have to receive a specific number of complaints before we look into a problem. We gather all available information on a problem. Your complaint is important to us.
 
For those of you that haven't seen it yet, there is a video of a LEAF being driven around a racetrack (Laguna Seca in California) for over 10 minutes with no adverse consequences to the vehicle nor the driver. Certainly, this would qualify as severe braking in a very intense real-world situation. While the video is fun to watch, it shows that the LEAF is a capable vehicle in extreme performance situations that most drivers will never see.

I strongly agree with those that say that you should have your local dealer take a look at your car. If your car (LEAF or anything else) is not performing as you expect it to, have the dealer look at it. Sometimes individual vehicles have issues that are not symptomatic of the model.
 
LEAFguy said:
For those of you that haven't seen it yet, there is a video of a LEAF being driven around a racetrack (Laguna Seca in California) for over 10 minutes with no adverse consequences to the vehicle nor the driver.

Thanks for the link. I was there the day before ripping Lotus Evoras around the track and sadly had committed myself and my LEAF elsewhere that day. I would have loved to haul around Laguna Seca in an EV.

Glad to see Nader is putting his LEAF to good use! I like seeing cars leave my dealership and ending up in the hands of fun loving owners.
 
Hi all,

I just experienced the same braking issue that was mentioned at the head of this e-mail. I was on the freeway and the car in front of me stopped suddenly. I slammed on the brakes and pulled to the right to get some more space. I also pulsed the brake pedal to flash my rear brake lights for the guy behind me. Then the tires completely locked up for about half a second and then I kept on going.

This was rather scary and unsettling. I'm pretty sure it doesn't have to do with regen, but there could be something with the anti-lock brakes, especially if I'm pulsing the brake pedal.

Thanks for bringing this issue up and letting me know I'm not alone with this problem.

Cheers,
Tim
 
With ABS, the last thing you want to do is pulse or pump the brakes. In a panic or hard stop you want hard and constant pressure on the brake pedal.


timk said:
I slammed on the brakes and pulled to the right to get some more space. I also pulsed the brake pedal to flash my rear brake lights for the guy behind me.
 
mogur said:
With ABS, the last thing you want to do is pulse or pump the brakes. In a panic or hard stop you want hard and constant pressure on the brake pedal.

Thanks for the tip. Why is pulsing or pumping the brakes bad? Does it confuse the ABS system? I guess I'm going to have to unlearn my skills that I learned with non-ABS brakes.

Still, I think this is a safety issue and I'm going to report it to Nissan tomorrow when their support number is available.

Tim
 
If you release pressure on the brake pedal, the ABS system will cease working and your stopping distance will grow markedly. Remember that ABS works by itself pumping the brakes some ten times a second or so. And, yes, the techniques we learned with non-ABS brakes are exactly backwards of what is desirable with ABS brakes. Also, if Brake Assist senses that you have backed off the brakes, it will disengage and the braking effort will fall significantly...


timk said:
mogur said:
With ABS, the last thing you want to do is pulse or pump the brakes. In a panic or hard stop you want hard and constant pressure on the brake pedal.

Thanks for the tip. Why is pulsing or pumping the brakes bad? Does it confuse the ABS system? I guess I'm going to have to unlearn my skills that I learned with non-ABS brakes.

Still, I think this is a safety issue and I'm going to report it to Nissan tomorrow when their support number is available.

Tim
 
Every owner of every new car owes it to themselves to take the car somewhere safe (racetrack, parking lot, long driveway) and WORK it over! Repeatedly, without mercy.

I mean hard. Brake like a kid just jumped into the street. Swerve like a gypsy just appeared out of the fog.

How will you ever know how the car behaves if you don't learn the car, practice the motions, and gain confidence in the safety systems?

You won't hurt anything except tire wear. :)

If my car behaved exactly as described in the OP, I'd take it to the dealer right quick! The brakes need to RELEASE on command, as this too is needed for safety. You don't want to poke the brakes in stop&go traffic only to get rear-ended for skidding to a halt.
 
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