Photo courtesy of EVs Enhanced.
Flip The Fleet (Henrik Moller, Daniel Myall and Dima Ivanov), Donald Love, Joe Barnett, Mark Nixon and Walter Larason
November 23, 2018, New Zealand.
We have become aware of over 60 reported failures (“failure” hereafter) of the electrically-driven brake control unit (called an ‘e-ACT Electrically-driven Intelligent Brake Control Unit’ by Nissan,”brake control unit“ hereafter) in Gen 1.2/1.3 Nissan Leafs manufactured between November 2012 and February 2016 (“vehicle” hereafter). We are aware of 46 reported failures in USA, 10 in the UK and Ireland, and 5 in New Zealand.
Our research has led us to believe that these failures can be attributed to faulty ‘Series-A’ firmware that is written into the brake control unit at the time of manufacture (or a subsequent firmware update to ‘Series-B’). Analysis of the vehicle’s fault code history after a failure indicates that the other systems in the car no longer get any response when trying to communicate with the brake control unit. In other words, it appears that the brake control unit ‘crashes’, causing a partial failure in the overall braking system of the vehicle.
We haven’t found anything that implies that these failures can occur in any other Nissan vehicle, or, any other electric vehicle. Specifically in relation to other Nissan Leafs, Gen-1.2/1.3 models manufactured in March 2016 and later have a revised ‘Series-C’ version of the brake control unit firmware, and we have not been able to find any reported failures in Nissan Leafs running this ‘Series-C’ firmware. Gen 1.1 models manufactured in 2011 and 2012, and Gen 2 ‘40kWh’ models now in production appear to be running fundamentally different classes of brake control unit firmware, and we have not been able to find any reported failures in these Nissan Leafs.
In their recollections of failures, some drivers have described pressing the brake pedal as they normally do, but braking seemed ineffective and stopping ability was reduced or non-existant. Our research has shown that in case of a simulated failure, reduced braking ability is still available to the driver but:
- requires further brake pedal travel,
- requires much more pressure on the brake pedal,
- results in lots of strange, loud clunking and chattering noises and
- results in increased braking distance.
In Nissan’s words, “In this [special Assist] mode, the brakes are operational, but may require more pedal effort”. We assume that Nissan’s definition of ‘special assist mode’ describes the failures we are writing about here.
Nissan has issued voluntary service recalls to update the firmware for affected vehicles sold in the USA, Canada and certain European Nordic countries in 2015/2016 from ‘Series-A’ to ‘Series-B’ firmware, but we are aware that failures kept occurring in vehicles which had this service campaign carried out (i.e. ‘Series-B’ firmware update apparently did not fix all of the problems present in the ‘Series-A’ firmware). Nissan specifies that their voluntary service campaigns were addressing a problem that could only occur in extremely cold climates of minus 20 degrees Celsius (minus 4 Fahrenheit) or lower. However, we have found failures that occurred in warmer climates of California and New Zealand, so we don’t believe the freezing temperature alone is the cause of the failures. Additionally, these service campaigns were either not made available or not compulsory for vehicles sold in the UK or Japan – almost exclusive sources for vehicles imported into New Zealand. We have been able to confirm that the ‘Series-B’ firmware is identical between right-hand-drive and left-hand-drive variants of the vehicle, and that the ‘Series-A’ firmware for generation 1.2 is identical between UK and Japanese models. We also have no information to suggest that the brake control units of the affected vehicles are different between the countries of first origin. Preliminary statistical analysis of the fragmentary data available estimates that between 2 and 15 such failures can be expected in New Zealand in the coming year if the number of these vehicles continue to grow at the rate seen over the past year.
Globally, there could be tens of thousands of vehicles that are currently running either the factory-installed ‘Series-A’ firmware or the updated ‘Series-B’ firmware, and are therefore prone to this failure. In New Zealand, specifically, we estimate there are around 2,400 potentially vulnerable vehicles, with a vast majority still running the factory-installed ‘Series-A’ firmware version.
Why we are concerned
We have become aware of a potential issue with the brake system in Nissan Leafs manufactured between November 2012 and February 2016. If you live in NZ, you can look your car’s registration number up on www.carjam.co.nz – on the first line “year”, the month of manufacture is listed in brackets, like “(2016-03)”. So far we know of at least five instances of partial brake failure in New Zealand and we are awaiting NZTA’s assessment of the risk and any potential remedies. Below, we set out what we know so far, but most importantly, we want to alert you to how you can react if you experience a brake failure: you may need to slam the brake pedal hard and right to the floor to get some braking! There will likely be strange noises, the brake pedal will feel rather different, and at first you might think there are no brakes at all. Note that even when pressing the brake pedal right to the floor, some individuals reported that they still had no braking force. The picture continues to be very uncertain, so if you can, please fill in the form on www.flipthefleet.org/leaf-brakes-logbook to share information about any issues you may already have experienced with your brakes. We would like to share your information with others to keep the EV community as safe as possible.
For those new to our project, Flip The Fleet is a community project that empowers New Zealand-based EV drivers to play a vital part in building a brighter future for electric transport in our country. As you browse our Discussion and Resources pages, you’ll find a wealth of information on EVs, both quantified by the data we collected, and, from personal testimony of our participating kiwi drivers.
What we know
Rather than writing a formal report, we would like to share what we’ve learned over the last few months via a ‘hypothetical-questions-and-answers’ structure, below. If there are some questions we’ve missed, please write to us at email@example.com and we’ll do our best to add them in as time allows. Here we go!
We understand and acknowledge that our findings don’t always please all the stakeholders, including vehicle manufacturers, importers, dealers, drivers and various other organisations. But being a citizen science project, it is our moral obligation to publish the important findings (especially if it’s related to safety!), warts and all, despite the negative impact these actions may have on ourselves, businesses, regulators and EV owners alike. The findings presented in this blog surrounding the reported failures of the e-ACT Electrically-driven Intelligent Brake Control Unit, perhaps, fall into the ‘negative results’ bucket.
As a quick reminder, if you have one of these vehicles, please consider registering it with us by clicking here, so we can learn more about these failures and keep you up to date.
We hope this is helpful!
If you have any further questions, feedback or comments, please post them to the discussion below – we would love to hear from you! We’re all volunteers at Flip The Fleet, so depending on our workload, we may take a while to reply, or just choose to leave it to our community to chip in.