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 braking performance and others to safety.   As most of these updates were released some time ago, in theory imported vehicles should already have been updated in their country of origin.  Unfortunately, this is very inconsistent and is often not the case.  If a vehicle was serviced by a switched on dealer overseas then it may arrive with all updates applied.  However, there are also far too many examples where dealers overseas have not completed any updates.

In our local New Zealand market, an additional complication has arisen.  The majority of the Leafs in our country are imported used from Japan and Nissan New Zealand has a general policy of not making firmware updates for imports available even to their own franchised dealers.  They claim that this is the importers problem to solve, so we have worked hard to support vehicle owners and importers with practical solutions to this problem which can be implemented on a vehicle anywhere in the world.

While the slightly older AZE0-1 (2014/2015MY) Leafs have a more problematic braking system as discussed here, fortunately brake system problems are far less common on AZE0-2 (2016/2017MY) cars, particularly those built after February 2016. There are a smaller number of early AZE0-2 cars built from December 2015 to February 2016 which have the earlier brake firmware version ending in ‘A’.  We have assisted a small number of customers with these earlier AZE0-2 vehicles that have had brake system failures.   Their issues were successfully resolved after updating to the later ‘C’ firmware.  

For Japanese models, 4NN1A is the earlier version and 4NN1C is the later version.  The changeover occurred during production in February 2016.  

For UK models of the same era, the original firmware version is 4NR0A and the later firmware is 4NR0C.  The changeover point to the later firmware version during production occurred later in 2016.

Based on our observations, we recommend that anyone with a Leaf running the early firmware to have the relevant 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.