Intelligent Brake Unit Replacement & Stroke Sensor

[Billabob1234]

Hello,

I posted in another troubleshooting thread about the braking failures I experienced with my 2015 Leaf. Basically upon power up the leaf entered a brake failure state, with "brake" and "warning" lights lit. In this state, the car will still go into drive/reverse, but when you press the brake pedal, it goes about 75% to the floor without applying any brakes, and then the ABS kicks in and the car will come to a grinding halt. Here is the thread I posted in before: https://www.mynissanleaf.com/viewtopic.php?f=30&t=25858&p=606899#p606899

The problem is intermittent. It happened to me twice in four months, and the second time was with a new 12v battery. The problem fixed itself both times. Needless to say, my wife and I didn't trust the car anymore and didn't feel good driving anywhere with our kids...

This problem is documented by a couple of people on the forum, and if you go to the NHTSA website, I saw 51 complaints for brakes for the 2015 Leaf alone, and most of them were similar to this failure. There is also a very thorough investigation into the issue on the FlipTheFleet website out of New Zealand.

The dealer quoted $3,000 parts & labor to replace the intelligent brake unit, which I was not keen on paying because I feel this is a serious safety issue that Nissan should cover despite my car being out of warranty.

I talked with Nissan Customer Service and they were not very helpful. They basically said that my car was out of warranty so there was nothing they could do. I am shocked and concerned that they were not more interested in diagnosing and resolving a serious safety issue. But after a few phonecalls and emails I could see they were not budging.

-------

Long story short, I needed to start using the Leaf again, so I bought an intelligent brake unit from a 2017 Leaf on ebay and installed it. On initial powerup there were some codes I had to clear, but everything seems to be working flawlessly. Time will tell if the brake failure comes back, but I am hopeful it will not based on info on this forum and other websites that the brake software was updated sometime in the 2016 model year and that supposedly fixed the issue.

A question I wanted to pose to you guys - the last step in the service manual procedure for replacing this unit says that I need to teach the stroke sensor zero point with Consult.

"Perform stroke sensor 0 point learning when electrically-driven
intelligent brake unit is removed and installed, or replaced. Refer to
BR-53, "Work Procedure".

I was planning to take the car to the dealer to have this performed after the install, but it seems that everything is working okay and I may not need to. Does anyone know what this zero point setting does and if it is needed if the car seems to brake and perform normally?

Thank you....
Bill

 

[Nubo]

I'd imagine zero-point is the system's definition of where in the stroke braking is considered to begin. I can't speculate as to importance. Any system whose firmware can cause a permanent malfunction years after being put in service is too "intelligent" for me to properly comprehend. :roll:

 

[Billabob1234]

:lol: Yes, intelligent is a strong word.

That's what I was thinking too.. like if the input shaft that connects the master cylinder to the brake pedal is a different length, then you would have to re-teach the zero point. I tried to get fancy and used a height gage to check the input shaft length on both cylinders. They were pretty much identical, so I believe that is a good sign.

 

[goldbrick]

It's possible the zero point accounts for different length shafts but I agree with the above that it finds the point where the braking motion starts or in effect just calibrates any offset between the sensor and shaft location. It's also possible the firmware will continuously adjust the offset to fine-tune the zero location as time goes by, but without knowing how the code is written that's impossible to know.

 

[EmilyC]

Hello,

I posted in another troubleshooting thread about the braking failures I experienced with my 2015 Leaf. Basically upon power up the leaf entered a brake failure state, with "brake" and "warning" lights lit. In this state, the car will still go into drive/reverse, but when you press the brake pedal, it goes about 75% to the floor without applying any brakes, and then the ABS kicks in and the car will come to a grinding halt. Here is the thread I posted in before: https://www.mynissanleaf.com/viewtopic.php?f=30&t=25858&p=606899#p606899

The problem is intermittent. It happened to me twice in four months, and the second time was with a new 12v battery. The problem fixed itself both times. Needless to say, my wife and I didn't trust the car anymore and didn't feel good driving anywhere with our kids...

This problem is documented by a couple of people on the forum, and if you go to the NHTSA website, I saw 51 complaints for brakes for the 2015 Leaf alone, and most of them were similar to this failure. There is also a very thorough investigation into the issue on the FlipTheFleet website out of New Zealand.

The dealer quoted $3,000 parts & labor to replace the intelligent brake unit, which I was not keen on paying because I feel this is a serious safety issue that Nissan should cover despite my car being out of warranty.

I talked with Nissan Customer Service and they were not very helpful. They basically said that my car was out of warranty so there was nothing they could do. I am shocked and concerned that they were not more interested in diagnosing and resolving a serious safety issue. But after a few phonecalls and emails I could see they were not budging.

-------

Long story short, I needed to start using the Leaf again, so I bought an intelligent brake unit from a 2017 Leaf on ebay and installed it. On initial powerup there were some codes I had to clear, but everything seems to be working flawlessly. Time will tell if the brake failure comes back, but I am hopeful it will not based on info on this forum and other websites that the brake software was updated sometime in the 2016 model year and that supposedly fixed the issue.

A question I wanted to pose to you guys - the last step in the service manual procedure for replacing this unit says that I need to teach the stroke sensor zero point with Consult.

I was planning to take the car to the dealer to have this performed after the install, but it seems that everything is working okay and I may not need to. Does anyone know what this zero point setting does and if it is needed if the car seems to brake and perform normally?

Thank you....
Bill

Did it solve the problem for you? We have the same issue on our 2016 leaf and Nissan want £5000 to fix it. We are wondering if it's possible for us to change it ourselves if we buy a spare part off ebay. We've already replaced the 12v and tried bleeding the brakes but still getting the intermittent brake issue.