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 ‘booster’ 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.

Nissan has released many firmware updates for the electrically-driven intelligent brake control module in different models of the Nissan Leaf. Some of these updates relate to improved performance and others to safety.  Unfortunately, in New Zealand the majority of these updates have not been made available by Nissan New Zealand to their franchised dealers.

We have known for some time that AZE0-1 (2014-2015 Model Year) Leafs have a design flaw with their Electric Driven Intelligent Brake (EDIB) system which in a small but significant number of cases had lead to the electronic system temporarily becoming completely unresponsive.  In this situation there is no braking force whatsoever within the first 3/4 of the brake pedal travel which of course can be highly frightening and dangerous as the driver may not instinctively know in this situation to press the pedal further all the way to the floor.  Nissan has released several firmware updates for this braking system in the years since its production, yet there has never been any acknowledgement of there being a problem.  Unfortunately, after years of monitoring and analysis of a large number of cases, we don’t have confidence that any of Nissan’s firmware updates have fixed the issue. However, the latest update does seem to result in improved brake feel and performance so we do still consider this as a worthwhile upgrade to be offered alongside normal servicing (aka brake fluid check/change which is probably the single most important service item on these cars).  We continue to spend time and effort on getting to the bottom of this issue and hope to be able to offer a highly cost-effective repair, but we are not there yet.  Surprisingly, in 2020 Nissan released a brand new replacement EDIB variant for the now 6-7 year old AZE0-1 Leaf and we do have a high level of confidence that these new units resolve the issues associated with the original part.  We are now stocking these replacement brake units for a fraction of the price of getting one through Nissan NZ. 

What is clear is that the firmware updates brings Leaf brake control modules up to later specifications beyond when any of these cars were actually built. Particularly in AZE0-0xxxxx (2013MY) models, an update is specifically intended by Nissan to improve the overall brake sensitivity at low speed.  Some owners of 2014-2015MY cars have also reported improved brake performance and feel following the update and we have experienced this ourselves in some cases. With the potential to improve feel, performance and safety, we recommend that anyone with an AZE0-0xxxxx or AZE0-1xxxxx Leaf is best advised to have the latest brake update performed if it is available to them. The graphic below shows the firmware versions to check if a car requires an update or not. This information is available on many diagnostics tools including the Pro version of LeafSpy.