Scary braking problem

[GerryAZ]

EVDriver,
I guess it wouldn't actually flat spot the tires because the ABS would keep them turning, but it would waste some rubber. I suppose I should find a safe place and do some testing to see if the 2015 is any better.

Jpadc,
What I experienced during sudden braking on the highway and confirmed through testing on my 2011 was clearly associated with brake assist. It had nothing to do with the hill holding feature.

Gerry

 

[jpadc]

Jpadc,
What I experienced during sudden braking on the highway and confirmed through testing on my 2011 was clearly associated with brake assist. It had nothing to do with the hill holding feature.

Gerry, I am just speculating here (and I don't know if the angular sensor was even on a 2011 LEAF). I'm just wondering how you are so confident its a brake assist problem?

It seems to me that if brake assist failed to operate properly, the result would be "no assist" not ongoing holding since the assist only facilitates "pressing" not "holding" of the peddle. On the other hand, the angular sensor is designed to hold the brake peddle in place for 2 seconds and as documented in the other thread, when it fails, it holds the brakes on even on flat surfaces. Again, I know nothing about this so I'm not claiming I know anything, just asking what it is about the assist function you believe is causing the holding?

 

[Ockendonleaf]

I think brake assist is a red herring put about by nissan to explain away a dangerous defect in some of its cars. When my car suddenly decelerated from 60 miles a hour to 30 miles a hour in 1 second ( I checked the dash cam footage) they told me that they had never heard of this problem then kept the car for 4 weeks before giving it back to me and telling me they could not fix it. I think they are trying to avoid a safety recall by trying to convince owners that this is normal and nothing to worry about. The mechanic that looked at my car also said he could change the brake servo but he did not think it would fix it and it would cost me £3500.00 to have it changed. If this was a safety system then why has nissan uk never heard of it and why do the brake lights not come on while the car is stopping. I have added a short video on youtube showing this https://www.youtube.com/watch?v=FJrQwPIanQ4

 

[Agkirk]

My brakes started acting up today. Went to a store and returned to the Leaf and backed up. Pressure on the brake pedal didn't stop the car, scary. More pressure caused the brakes to slow down my motion and stopped it. A lot of pressure. Made and still makes a loud squawk at this point but stops the car.
Checked the brake fluid, appeared to be lower than the minimum line so went to NAPA and got a the $4 bottle of DOT brake fluid and put about 2-3 oz in the reservoir. Still makes that noise and would be considered unsafe to drive. Seemed like a lot of fluid and don't see any leaks on the ground. As the car comes to a stop after the squawks I can hear what sounds like something continuing to rotate another ten turns.
Yellow and Red caution lights are on, BRAKE light is on, Emergency brake works and releases. ABS, Traction Control light are on as is the one to the right of the ABS light.

Anyone have any ideas. My nearest Nissan dealer is 90 miles and I probably can make that without rear-ending someone, but it would help if there were a simple fix. I've tried the dealers service before but it is sparse and don't always return calls.

Edit Reposted in http://www.mynissanleaf.com/viewtopic.php?f=30&t=18283 Brake failure on power up.

 

[jpadc]

Anyone have any ideas. My nearest Nissan dealer is 90 miles and I probably can make that without rear-ending someone, but it would help if there were a simple fix. I've tried the dealers service before but it is sparse and don't always return calls.

My idea would be to park the car in the street out front of your house. Call Nissan Road Side Assistance (phone number in your owners manual) and tell them the car has left you stranded and they will tow the car to the dealer for service at their expense. That is what the warranty is for.

 

[RegGuheert]

Anyone have any ideas.

Check the voltage of your 12-V battery. First pop the hood and close all the doors. Let the car sit for 30 minutes. Then measure the voltage without opening any doors.

 

[Agkirk]

I've narrowed the problem/sounds down to the silver colored unit on the passenger side firewall. It may be part of the ABS as well as an electric hydraulic pump for the brakes. When I depress the brake pedal about an inch it starts to make a nice smooth rotational sound. When I depress the pedal another inch or so it shudders and the four or so hydraulic lines attached to it vibrate violently. The brakes come on at this point, probably full tilt. There appears to be no gradual application of the break pads.

I'm 90 miles from the nearest dealer so it at least 2 hours plus a QC to have them look at the problem. I was going to go with the Roadside assistance trucking but the dealer reminded me that the "tow" would be at my expense if they found a wire had been damaged by mice or rabbits. My rabbits are friendly, way too friendly and have attacked the wire that goes to the charge port door release solenoid. Looked for other damage but could find none, at least anything near the ABS box. When it get cooler today I will get down on my knees and see if they nibbled a wire coming from the wheels, where a rotational sensor might be located.

I'm thinking that over and trying to figure out just where this problem started and if others have had a similar problem.
I checked the 12V battery and it reads 12.5 Vdc after a 30 minute wait. I did note that the red battery icon illuminates, as do the ABS and several other caution lights.
EV charges OK and drives just fine, just doesn't stop slowly! Trip to the dealer is all highway with few full stops and light traffic, so I could make the trip but it would be SCARY!

Didn't see anyone tell what was wrong when they observed this problem except for the 12V battery failure. I the little silver box the ABS or is there more to it than that?

 

[jpadc]

I did note that the red battery icon illuminates, as do the ABS and several other caution lights.
EV charges OK and drives just fine, just doesn't stop slowly! Trip to the dealer is all highway with few full stops and light traffic, so I could make the trip but it would be SCARY!

All the more reason to believe that RegGuheert is right that this is a 12 volt battery issue. Your profile indicates we are talking about a fully warranted 2015. Even adding the brake fluid (if not exactly the right type) might cause warranty issues. My point is you do not have to drive it to the dealer and risk a problem (for which you would be liable). Nissan will tow it there at their expense. Just let them deal with it worry and cost FREE!

 

[Firetruck41]

Sounds like a 12v problem, not a "brake" problem. It probably affects the brake vacuum assist, which is probably powered by 12v, as opposed to engine vacuum in an ICE. It would be like the engine dying on an ICE and then the brakes requiring a lot of pedal pressure to bring a car to a stop. That would not be a "brake" problem, but a vacuum problem.

 

[TimLee]

...
I checked the 12V battery and it reads 12.5 Vdc after a 30 minute wait. ...

Checking voltage is often misleading in evaluating the condition of a 12V battery.
Have a free test done at your nearest auto parts store.
But even their testers can be misleading sometimes.

When my 12V apparently shorted a cell, it produced adequate voltage right after lenghty charge.
But with use voltage would sag and had one instance of the scary non-braking.

 

[Nubo]

My brakes started acting up today. Went to a store and returned to the Leaf and backed up. Pressure on the brake pedal didn't stop the car, scary. More pressure caused the brakes to slow down my motion and stopped it. A lot of pressure. Made and still makes a loud squawk at this point but stops the car.
Checked the brake fluid, appeared to be lower than the minimum line so went to NAPA and got a the $4 bottle of DOT brake fluid and put about 2-3 oz in the reservoir. Still makes that noise and would be considered unsafe to drive. Seemed like a lot of fluid and don't see any leaks on the ground. As the car comes to a stop after the squawks I can hear what sounds like something continuing to rotate another ten turns.
Yellow and Red caution lights are on, BRAKE light is on, Emergency brake works and releases. ABS, Traction Control light are on as is the one to the right of the ABS light.

Anyone have any ideas. My nearest Nissan dealer is 90 miles and I probably can make that without rear-ending someone, but it would help if there were a simple fix. I've tried the dealers service before but it is sparse and don't always return calls.

The loss of fluid is worrisome. It doesn't just disappear. The problem now might be trapped air but the missing fluid needs to be explained. Personally I'd have it hauled to the dealer.

 

[Agkirk]

My scary brakes problem went away ! Took 72 hours. I downloaded the maintenance manual, studied it using the LSP provided DTC's and pulled the 20 amp fuse from the passenger side of the motor compartment. Looked good so attempted to replace and it dropped into fuse box. Went to Auto Zone and got another. Took the interfering relay out, successful replaced fuse (and relay ). Tried brakes and all is good !

e: 20151027 I don't think there was a problem with the brake fluid. It appeared low because the Low Line is at the reservoir mold line and in my hast to solve the apparent emergency and filled it to the Max Line.
I also noted this link on this Forum that might be of help. While not the exact symptoms, close enough in the world of Brakes not working correctly. http://www.mynissanleaf.com/viewtopic.php?f=30&t=20770
and here http://www.mynissanleaf.com/viewtopic.php?f=30&t=18977&start=10

 

[harrier]

Safergov will not go after the manufacturer based on your one complaint. The benefit of posting there is that if a similar complaint reappears, then the regulators can help get it solved. If the dealer fixes, and there is nobody else with the problem, your complaint will disappear into the ether.

However, the next guy with that problem may not get great service, and your complaint will help theirs.