Toyota Motor Sales, USA, Inc., is advising the National Highway Traffic Safety Administration (NHTSA) of plans to conduct voluntary safety recalls of approximately 701,000 Model Year 2010-2014 Prius vehicles to update the motor/generator control ECU and hybrid control ECU software. This is part of a global recall for the issue.
According to the information Toyota is providing Prius customers in the US, the problem resides in the Intelligent Power Module (IPM), which is inside the Hybrid Inverter Assembly. The inverter converts high-voltage direct current (DC) stored in the high-voltage (HV) battery into high-voltage alternating current (AC) for the motor/generator. It also converts AC into DC during regenerative braking for storage in the HV battery. According to Toyota, due to problems with the software, certain transistors in the IPM could become damaged when operating the vehicle under high-load driving conditions, such as accelerating during highway driving.
If this occurs, various warning lamps on the instrument panel will illuminate. In most cases the vehicle will enter a fail-safe mode, resulting in reduced motive power in which the vehicle can still be driven for short distances. In limited instances, the motor/generator ECU could reset, causing the hybrid system to shut down, resulting in the vehicle stopping while being driven and increasing the risk of a crash.
Toyota has received no reports of accidents or injuries associated with the condition.
As a remedy, later this month Toyota will send notification to owners of affected vehicles. Any authorized Toyota dealer will perform a software update to the Motor Generator ECU and Power Management ECU at no charge. Additionally, if the vehicle has the condition present, the inverter assembly will be replaced prior to the software updates.
Toyota recommends that until the remedy is performed, drivers should avoid placing a high load on the hybrid system by avoiding full throttle application, when possible.
No other Toyota or Lexus models are affected, according to the company.
In a separate recall, Toyota is pulling approximately 260,000 Model Year 2012 Toyota RAV4, 2012-2013 Toyota Tacoma, and 2012-2013 Lexus RX 350 vehicles sold in the United States.
Toyota will update the skid control ECU software on these models in order to address an electronic circuit condition that can cause the Vehicle Stability Control, Anti-lock Brake, and Traction Control functions to intermittently turn off. If these systems are off, standard braking operation remains fully functional.