February 12, 2014 at 3:30 pm

Toyota recalls 2.2 million vehicles for software upgrades

Washington — Toyota Motor Corp. said Wednesday it is recalling 2.2 million vehicles worldwide to reprogram software to address two separate issues, including about 960,000 vehicles in the United States.

The recalls includes about 1.9 million 2010-2014 Prius hybrid cars, including about 700,000 in the United States, and 295,000 North American built 2012-2013 Lexus RX350, Rav4 and Tacoma vehicles, including 261,000 in the United States.

In both cases, Toyota dealers will reflash the software. Toyota spokesman John Hanson said the software upgrade is currently available for the Prius and will be available for the other vehicles in a couple of weeks. Dealers will have to physically upgrade the software, Toyota said.

Toyota said the Prius vehicles could abruptly stop on the highway or enter “limp home” mode with reduced power. Toyota started receiving reports of Prius owners losing power or limping home in May 2011 in fail-safe mode. Last year the investigation into the issue determined the Prius V vehicles didn’t have the same issue. Toyota determined that excessive stress on the transistors could result in damage, which could cause a specific microchip in the electronic control module to reset, resulting in hybrid systems shutting down rather than going into fail-safe mode. Toyota will update the hybrid control and motor/generator software.

If owners have problems before receiving the upgrade, dealers will replace the inverter assembly with a new one. Toyota will reimburse owners who have previously replaced the inverter assembly.

In the smaller recall, Toyota said the brake actuator that adjusts the fluid pressure of each wheel could be damaged by oxide film increasing resistance which could illuminate the warning lights and could make the anti-lock brakes or traction control systems inoperative. Toyota said it first received a field report of the issue in July 2012.

After a lengthy investigation, Toyota found a small gap in riveted parts may have led to the problem. The investigation found that the supplier changed the riveting process in March 2012, causing the rivet hole to be slightly bigger, leading to momentary electrical contact failure. The new software will remove oxide film by applying voltage when the resistance momentarily becomes high.

Toyota said it has received no reports of accidents or injuries associated with either condition.

dshepardson@detroitnews.com