Nissan North America, Inc. (Nissan) is reaching out to the owners of certain 2023 Ariya vehicles due to an issue with the inverter software. This problem may trigger the inverter to detect a short circuit, causing a shutdown of the EV system and a loss of drive power.
The Discovery of the Problem:
Nissan first became aware of this issue during a production trial involving an Ariya vehicle in January 2022. In this trial, the electric motor abruptly shut off shortly after the vehicle began moving at low speed. A diagnostic trouble code (DTC) revealed a short circuit inside the motor, although no actual damage to the motor or its components was observed. A deeper investigation into the problem found that in some rare instances, conductive fibers generated during the operation from the slip ring in the motor could lead to a momentary short circuit between the electrodes.
Understanding the Problem:
According to the defect report, the root cause of the issue lies in conductive fibrous shavings from the drive motors’ slip ring assembly. These shavings can occasionally cause a momentary short circuit between the two slip rings. When this occurs, the fibrous shavings are instantaneously burned out, causing no harm to any vehicle components. However, when the inverter detects a momentary over-current due to the short circuit, it reduces motor torque to protect the internal components of the controller. This leads to a loss of drive power, and an “EV System Off” message is displayed on the dashboard to alert the driver.
In the event of this issue occurring, the torque to the driven wheels is cut off. This continues until the fail-safe mode is released, which requires turning the vehicle off and then back on. An unexpected loss of motive power while driving at high speeds could potentially increase the risk of an accident.
To address this safety concern, Nissan dealers will reprogram the inverter software to enhance the fail-safe protocols. This proactive measure aims to prevent such short circuits from impacting the driving experience and maintaining safety for the driver.
Nissan has designated this recall as R23C6 and the National Highway Traffic Safety Administration (NHTSA) has assigned the campaign number 23V-657 to this recall.