Scary reduced brake power / pedal feel

[Anonymous]

Well I got a call from the dealership late today. It appears that it needed a programming patch and that the ABS system was not properly communicating on the CAN bus to the main computer. They said they also checked all the grounding.

The car is driving properly now but they wanted to keep it overnight and check it again in the morning.

I'll have the paperwork details when I pick it up from the dealership tomorrow. Will post anything I learn tomorrow.

 

[cwerdna]

^^^
Yes, we'd all love the details. Hopefully it's resolved.

After you get the car back w/the details of what they did, I'd file a safety complaint w/NHTSA at http://www.safercar.gov/" onclick="window.open(this.href);return false;.

For the Canadians, please file an equivalent w/your NHTSA equivalent (Transport Canada?) after they attempt to resolve (or blow you off).

 

[RegGuheert]

Well I got a call from the dealership late today. It appears that it needed a programming patch and that the ABS system was not properly communicating on the CAN bus to the main computer. They said they also checked all the grounding.

The car is driving properly now but they wanted to keep it overnight and check it again in the morning.

I'll have the paperwork details when I pick it up from the dealership tomorrow. Will post anything I learn tomorrow.

I wonder how that could just crop up in MY2015s and not affect MY2011s on.

I will point out that whenever the Nissan dealer connects a LEAF (or any car) to the computer for reprogramming, the first thing they do is connect the 12V battery to a fancy charger to ensure the don't brick your car due to a low battery.

It is quite possible that the communications problem was caused by a low battery and that charging it was the real fix.

I recommend that if you ever experience this again that you raise the hood and measure the voltage of the 12V system.

 

[TimLee]

This Saturday my 2015 SL with ~10K miles on it had the exact same thing happen. ...

You should update your profile delivery date to the vehicle you currently have.
That date is for the 2013 you had.
If you have both, better if you add signature that clarifies the point.

Glad dealer was able to fix the problem.
But agree that 12V battery voltage could also be a factor.
Very troubling that the LEAF braking can behave so badly without detecting the fault.

 

[Anonymous]

You should update your profile delivery date to the vehicle you currently have.
That date is for the 2013 you had.
If you have both, better if you add signature that clarifies the point.

Thanks Tim I've updated my profile. My first Leaf (the 2013) saved my life in a near fatal crash with two semis last August! If I could figure out how to post pictures I'd post a RIP photo of my 2013 SL.

The quote "He lived" should be inscribed on the photo!

 

[Anonymous]

Ok. So I have the Leaf back now and here is what the dealership did verbatim from the service ticket.
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CUSTOMER STATES VEHICLE WILL NOT STAY IN PARKED POSITION KEEPS MOVING FORWARD EVEN WHEN BRAKE IS APPLIED. STARTS TO MAKE A GROWLING/GRINDING NOISE BUTS KEEPS MOVING FORWARD HAS TO SHUT OFF VEHICLE TO STOP ADVANCEMENT CCHECK/ADVISE !!!!!! DO NOT DRIVE VEHICLE PUSH INTO STALL !!!!

FOUND SEVERAL CODES. UI000, UII0D, P3195, UI00B, UIA05, U0428, VEHICLE HAS NO BRAKING 4.00 CALLED TECH LINE AFTER INSPECTING. FOUND BRAKE SYSTEM NOT COMING UP IN ALL DIAGNOSIS. CAN COMMUNICATION ISSUE WITH BRAKE AND ABS UNIT. TURNED VEHICLE OFF. DISCONNECTED INTELLIGENT BRAKE UNIT AND ABS. CHECKED FOR POSITIVE VOLTAGE AND GROUNDS. FOUND NO ISSUES. REMOVED CONNECTOR COVERS AND CHECKING PIN FIT. FOUND A FEW PINS ON BOTH CONNECTORS A LITTLE LOOSE. TIGHTENED PINS AND RECHECKED. RECONNECTED AND CLEARED ALL CODES. NO CODES CAME BACK. BRAKE SYSTEM LOADS UP AND BRAKING IS WORKING. TEST DROVE COUPLE MILES AND NO ISSUES. LEFT OVER NIGHT AND REDROVE NEXT DAY. ALL SYSTEMS WORKING AND NO OTHER ISSUES FOUND.
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So contrary to what they told me yesterday that there was a programming patch applied. The repair ticket boils down to some loose pins. Nice to know the brakes can fail like this just with loose pins. Furthermore, loose pins when the car is only 5 months old! Will be filling a report with the NTSHA.

 

[RegGuheert]

So contrary to what they told me yesterday that there was a programming patch applied. The repair ticket boils down to some loose pins. Nice to know the brakes can fail like this just with loose pins. Furthermore, loose pins when the car is only 5 months old! Will be filling a report with the NTSHA.

Wow!

I'm an electrical engineer, but I'm not sure what tightening loose pins entails. Does anyone know what kind of connector pins they are talking about?

Thanks for the follow-up!

 

[MJuric]

Well I got a call from the dealership late today. It appears that it needed a programming patch and that the ABS system was not properly communicating on the CAN bus to the main computer. They said they also checked all the grounding.

The car is driving properly now but they wanted to keep it overnight and check it again in the morning.

I'll have the paperwork details when I pick it up from the dealership tomorrow. Will post anything I learn tomorrow.

I got my 2015 in Dec and have had probably 4-5 instances where I was braking and then the pedal seems to go soft and then I have to press much harder down on the pedal in order to get the car to stop. The first couple times it was so minor that I dismissed it as simply a "Different feel" of the electric vehicle or a minor blip in B Mode. This AM however I had an incident where I would describe similar to a master cylinder or power booster failure. I was braking and then nothing. Had to slam on the brakes very hard in order to get the car to stop.

I've never experienced this from a dead stop only while in operation.

Thoughts?

 

[QueenBee]

. Nice to know the brakes can fail like this just with loose pins.

Not sure what that means either but I think it's important to note that the brakes didn't fail, the power assist failed which while I can only imagine how scary that is, is not as big of a deal as if the brakes actually failed.

 

[RegGuheert]

Not sure what that means either but I think it's important to note that the brakes didn't fail, the power assist failed which while I can only imagine how scary that is, is not as big of a deal as if the brakes actually failed.

When the Nissan technician reprogrammed the brake controller on my LEAF, he did not know to recharge the ultracapacitor used for the power assist. They told me that they could not return the car to me because it had no brakes. I asked what that meant and they said that there was no pedal. It went all the way to the floor.

To me, that sounds like the brakes failed without the assist in place. It also matches some of the other reports made here.

Apparently the LEAFs in MY2013 and beyond have moved to a hydraulic accumulator for energy storage, so perhaps the failure modes are completely different.