Sounds pretty bad!!!
Version 1: Log book reports up to 17 December 2018
Since publishing our original post on these faults, Flip the Fleet has now received 22 reports of problems with Nissan Leaf brakes, all but one of which occurred in New Zealand. We estimate that 9 of these resulted from a firmware fault in the Electrically-driven Intelligent Brake Control Unit (EDIB) which causes the braking system to become unresponsive. There appear to be two states following the EDIB fault: one where impaired, but still relatively effective braking can be achieved with the engagement of the Leaf’s Anti-lock Braking System (ABS); and a second state where the ABS does not engage and the driver alone arrests the car by applying intense pressure on the brake pedal and stopping power is much reduced. The same car can exhibit both states of the EDIB fault but the relative frequency and conditions that trigger the alternate states are unknown. The New Zealand Transport Agency (NZTA) has conducted a single test of a Leaf on a roller brake machine in the EDIB fault mode (which appears to have been in the first state) and concluded that it meets the WoF requirements. This is very encouraging, but we believe that further testing is required to fully evaluate the consequences of brake issues and especially to explore the existence of the second severely impairing braking state that appears to be associated with the ABS not being engaged to help arrest the vehicle.
If the observed probability of EDIB fault per car does not change, and if the 2013-2016 fleet size continues to double annually, we can expect about 11 such faults over the coming year. This observed incidence rate is probably underestimated and the sample size is small, so the statistical uncertainty band for this prediction ranges from 6 to 21 faults in the next year.
In addition to the 9 cases with the EDIB faults, another 13 cases of a diverse range of braking issues have also been reported that do not appear to relate to the primary EDIB fault that is being observed. They range from relatively minor to serious events. Many may be solved by recalibration of the existing brake firmware or potentially other forms of maintenance.
The descriptions of the events leave no doubt of the distress of the affected drivers and potential risk and expense involved:
- one returned the vehicle to the dealer and bought an internal combustion vehicle instead;
- one is urging that no more Leafs are sold until the problem he experienced is fixed;
- one nearly rear-end a truck but was able to veer left into an empty lane and turn left again because the traffic light happened to go green at the same moment;
- one nearly hit a rapid charging station because the fault occurred as they were pulling in to recharge;
- one ended up in the middle of an intersection and is now too frightened to drive the car;
- one would have incurred over $1,500 in vehicle recovery costs had they not had AA Roadside Recovery policy, and potentially several thousands of dollars in replacing the full brake module.
Until future monitoring and more extensive research is conducted to better assess and manage any risk, Nissan drivers can best help protect themselves and others by becoming fully aware of the potential for brake faults and what to do if it happens to them. Based on our research and testing, we believe that in most EDIB fault situations, slamming the brake pedal right to the floor and exerting as much force as you can muster will be the most effective way to stop the vehicle. Ignore any loud graunching sounds and juddering of the car – they are a normal part of the brake assist mode. Unfortunately, during normal EDIB behaviour many Leafs tend to have quite touchy brakes where gentle and variable brake application may be required, so many Leaf owners may be subconsciously conditioned to never firmly apply the brakes.
Recurring faults sometimes happen in the same car, even in quite quick succession, so it is imperative that you stop and seek help immediately after the first occasion. Regular servicing and maintaining a healthy 12V battery may also help reduce the likelihood of a fault, especially of minor types. Never drive the car if brake warning lights appear at start-up.
If a fault happens to you, please use LeafSpy Pro to read the DTCs and ECU versions, accessible via the Service Menu and send them to Flip the Fleet along with a log book report. Then take your car to a service agent, preferably a certified Nissan dealer that is experienced in fixing and servicing Leafs so they can inspect the ECU and DTC information and report to Nissan New Zealand. It is best practice to record then clear all historical DTC notifications so that you can track the recent performance of your car.
Insufficient information is presented here for a fully informed scientific judgement of whether sufficient risk exists for NZTA and Nissan to intervene and remedy the faults; nor can the available information reliably rule out if intervention is needed. Flip the Fleet is not mandated or equipped to make an overall risk assessment – that is a job for NZTA alone. Nissan have not acknowledged the existence of these apparent faults, nor indicated whether the brake firmware ‘C’ updates seen in some overseas cars will fix the braking problems described in this study.
We urge the NZTA to urgently complete a formal risk assessment and advise answers to three fundamental and interlinked questions:
- Are the 2013-2016 Leafs safe to drive?
- Are firmware remedies available to fix the problems observed here?
- If a remedy exist, will it be made available at an affordable price for drivers of Leafs imported second-hand to New Zealand?
This is an update to our original post entitled Reported failures of the e-ACT Electrically-driven Intelligent Brake Control Unit in Nissan Leafs manufactured between November 2012 and February 2016 which was posted on Flip the Fleet’s website on November 23, 2018 (click here to view). Flip the Fleet is a ‘citizen science’ coalition of electric vehicle (EV) owners from throughout New Zealand that is creating a communal database on all manner of performance indicators for EVs in New Zealand conditions.
We were aware of five reported cases of one type of brake fault when we posted that original report. Since then we set up an online form for Leaf owners to report any braking issues at www.flipthefleet.org/leaf-brakes-logbook (hereafter referred to as the “brakes logbook”). We subsequently received 16 new reports of braking aberrations in Nissan Leafs from New Zealand and an additional case from Denmark.
This report provides an interim summary of the information received to date to help Leaf owners, dealers and decision-makers form a response. It is intended as a “living document” because we will update the case histories as more logbook reports are received, with subsequent analysis and recommendations as better information comes to hand.
This report starts with a summary of the case histories received so far. We then describe different categories of unexpected brake behaviour and their symptoms. These observed cases are next analysed together with results of some road tests of simulated EDIB faults to narrow down potential causes and their implications. We end by listing recommendations about what drivers and owners can do to help minimise risks of future brake faults. Our questions to and responses from Nissan New Zealand, the Motor Industry Association and NZTA are also recorded in full appendices to highlight the political and economic challenges in securing a remedy to the braking faults.
An online report was posted at https://flipthefleet.org/2018/leaf-brakes-failures/ on 23 November 2018. The potential risk and preliminary descriptions of the original five cases were described in that report and around 1,200 participants in Flip the Fleet received an alert about the issue and invitation to fill in the brakes logbook at that same time. There was considerable media coverage in New Zealand in the ensuing week, so the request to fill in the logbook reached many other Leaf owners who were not part of Flip the Fleet. The drivers of all five of the original brake fault cases have all now submitted a logbook report in order to standardise the information as best as possible. Respondents were asked to describe the incident and report warning symbols on their dashboards, approximate temperature, their subsequent reporting and fixes of the problem and whether they had 12V battery problems or 12V battery replacements just before or after the incident(s). Records of brake firmware identifiers and Diagnostic Trouble Codes (DTCs) were recorded (usually by LeafSpy Pro app) if available. The current version (v1) of this report includes all logbook reports of brake faults up until 12 December 2018.
Recent posts on New Zealand EV Facebook group forums and emails to email@example.com have also described braking concerns or events for Leafs for which we have not yet received a formal logbook report. An additional report of braking problems in a Mitsubishi Outlander was also received which has not been considered further in this analysis.
We conducted a small number of road tests of simulated faults on the 10th and 24th of November. In the first set of tests, the stopping distance of a 2014 Leaf was measured by two drivers who each hit the brakes as hard as they could at the point they passed a road cone placed alongside a deserted straight and sealed road in dry conditions. Stopping distance was measured in trials at 30, 50 and 100 km/h. The EDIB fault was then triggered experimentally by sending a command over the CAN Bus and the trials repeated. On 24th November, two of the original five drivers who had experienced real EDIB were asked to test emergency braking in another 2014 Leaf that had the same experimentally triggered fault. A third driver (one of our authors of this report) also tested the fault mode at a variety of speeds. A home built pressure sensor was used to approximately measure pressure applied to the brake pedal. The aim of the 24 November trials was to establish whether our experimental intervention created a qualitatively similar experience (e.g. “feel” of the brake pedal and noises) as those experienced when the actual fault occurred. More details of the methods and results are provided in Appendix 5. Our simulations were not intended to be full scientific tests or measures of the increased stopping distance – rather they were conducted to assess the broad nature of the EDIB fault, and provide a preliminary estimate of the scale of any impairment of braking.
A search of overseas social media forums and websites revealed several instances of brake faults which we reported in a general way in our original report. The reports are referenced in Appendix 4.
Originally we used the term “brake failure” in a generic sense to capture all manner of unexpected and reduced braking performance issue. This perhaps caused some unintended alarm, so we now use the term brake fault. Unless specified, at no time does our use of the term fault mean catastrophic failure of brakes where there is no resistance to arresting the car. For consistency with the NZTA reports we will use the term Electrically-driven Intelligent Brake (EDIB) in this report (see Appendix 1 for clarification).
The term MY for Model Year is used in the car industry. This report focuses on MY2013 to MY2016 which are all MY2013 to MY2015 cars and some MY2016 cars manufactured from November 2012 to February 2016. The MY provides a guide for when changes were made to the EDIB version. A MY2014 car manufactured in late 2013 may be called a 2013 car in New Zealand, but have the EDIB for a MY2014 car.