The Nissan Leaf features an ‘electrically-driven intelligent brake control module’. Simply put, this is an electrically-assisted brake master cylinder rather than a vacuum-assisted brake master cylinder as found on a traditional car with an internal combustion engine.
The Leaf’s brake master cylinder features it’s own integral control unit which interacts with other control units in the vehicle. It has the ability to command light braking requirements to be performed through regenerative braking using the traction motor only or by a combination of this and the hydraulic brakes.
The software in the brake control module on MY2013-2015 Nissan Leafs built in all markets around the world contains a fault which in rare cases can lead to the brakes going into a failure mode where the brakes are still operational, but require significantly more pedal effort and stroke to operate. Nissan has a firmware update which reportedly fixes this issue which they initially offered as a voluntary service campaign in both the US and UK, but it was later escalated to a proper recall in the US.
In what seems to be a concerning trend, it appears that the update was never offered for models built and sold in Japan despite clear evidence that these models are also affected.
We are now aware of several cases in New Zealand of brake failure occurring on 2013-2015 Leafs. In all cases, the car was being driven at the time. In at least one of these cases the driver narrowly avoided an accident. All vehicles were JDM models which had not been updated at the time of the incident. Following an inspection of three of these vehicles after the event, we concluded that the evidence suggested a firmware problem rather than a mechanical or electrical problem. We have no way of knowing for sure if Nissan’s existing firmware update for these control modules is indeed a fix for this rare issue or not. The described symptom seems to fit the types of failures that have been observed, but the cause that was given by Nissan USA as an as an explanation to the National Highway Traffic Safety Administration (NHTSA) does not.
What is clear is that the firmware update brings all 2013-2015 Leaf brake control modules up to late 2015 specifications beyond when any of these cars were actually built. Particularly in MY2013 models, the update is reported by Nissan to improve the overall brake sensitivity at low speed (MY2013 cars were subject to an earlier voluntary service campaign to fix this issue again with a firmware update). Some owners of 2014 and 2015 cars have reported improved brake performance and feel following the update, but we have not confirmed this ourselves. Between this and the chance of resolving a potential safety issue, we currently recommend that anyone with a 2013-2015 Leaf is best advised to have the update performed if it is available to them. The graphic below shows the relevant firmware versions to check if a car requires the update or not. This information is available on many diagnostics tools including the Pro version of LeafSpy.
We already have the ability to perform this update, but we take no satisfaction in knowing that currently Nissan NZ has not yet offered this update to their dealers. With the number of 2013-2015 Leafs in NZ, any successful update campaign will need to be distributed to cover all of our cities and regions within any reasonable length of time. Nissan’s existing dealer network is the obvious choice to be utilised for completing this work. We are assisting a group in advising Nissan management in both New Zealand and Japan as well as NZ government officials regarding the technical details of the situation.
Please feel free to contact us if you would like to discuss this issue further.