Fiat 500e EVs Recalled For Software Glitch That Can Stall Motor

Chrysler has issued a safety recall for the Fiat 500e to fix a software issue that can potentially stall the car.

Posted by the National Highway Traffic Safety Administration (NHTSA) last week, the recall includes 2013 to 2015 Fiat 500e cars. Chrysler said that 5,660 cars are affected, which is estimated to be the entire U.S. production run of the 500e.

The problem stems from a software glitch that affects the way the Electric Vehicle Control Unit (ECVU) talks to the Battery Pack Control Module (BPCM). Chrysler described the problem and its safety risk in more detail in the recall report:

In the event that the BPCM places the battery in limp home mode, by design there should be no requests to accept regenerative current to the battery. As a result of the software incompatibility, the EVCU does not recognize the limp home mode status and erroneously directs regenerative current to the battery pack causing an electrical system shut down to occur.

When this error occurs, the vehicle will conduct a general shut-down by opening the EV battery pack contactors causing a loss of motive power which may increase the risk of crash.

The high voltage battery provides energy to the traction motor. Safety, brake and steering systems are powered by the 12V battery on the vehicle and are unaffected. The system can be reset and perform normally after cycling the ignition key up to three times.

Chrysler said the faulty 500e EVs may not give a warning when it goes into limp home mode, so drivers may be unaware that the car could stall.

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The software that includes this glitch was put into production on March 13, 2014. The update included “improvements in charging system robustness, diagnostic capability and range estimation over life,” according to Chrysler. Two months later, the carmaker issued a Technical Service Bulletin for all 500e EVs built before March 2014 to update their computers with the same software.

Chrysler said that new software fixing the BPCM glitch went into production last October, but doesn’t explain why it took another six months to issue a recall for the 500e EVs already on the road.

This latest software glitch marks the third recall for the 500e. In 2013, Chrysler recalled 270 of the battery electric cars to check that the halfshaft bolts were properly tightened. In 2014, a problem with the power inverter module led to the recall of 4,141 500e cars.