US Safety Agency Launches Probe of Fiat Chrysler Vehicles

— -- A million vehicles produced by automobile manufacturer Fiat Chrysler are being investigated over the risk of a potentially deadly problem with gear shifters that may contribute to allowing the cars to roll away even when placed in park.

The National Highway Transportation Safety Administration launched the probe Tuesday into certain model years of the Dodge Ram pickup truck -- Fiat Chrysler’s top selling vehicle -- as well as the Dodge Durango. The investigation comes on the heels of an April recall of Jeep Grand Cherokees, also produced by the company, over a similar issue that the company remedied by installing new software with a fail-safe to put the car in park automatically.

The NHTSA’s inquiry will look into the electronic transmission shifters and rotary gear controls in the cars. The agency says it has registered 43 complaints so far, including 25 crashes or fires with nine resulting injuries. In 34 of the cases recorded by the NHTSA, the vehicles allegedly moved despite being set to park.

A company spokesman Tuesday said, “Fiat Chrysler Automobiles U.S. is cooperating fully with the NHTSA’s investigation, the scope of which is limited. Other vehicles equipped with rotary shifters are not included. In accordance with prudent practice, the Company joins [the] NHTSA in urging all drivers to use their vehicles' parking brakes.”

The issue with the company’s Jeeps turned deadly in June when actor Anton Yelchin was killed after his Grand Cherokee rolled down his driveway, pinning him against a brick mailbox stanchion and metal gate. His family has since filed a wrongful death lawsuit against Fiat Chrysler, claiming the accident was preventable. Fiat Chrysler Automobiles, while extending its “sympathies to the Yelchin family for their tragic loss,” said it cannot comment further because the matter is in litigation.

Yelchin’s vehicle was the model cited in the April recall but no definitive link has been proven between his death and the alleged flaw.

Sean Kane, the president of Safety Research and Strategies, a research firm specializing in motor vehicle and consumer product safety, said the electronic shifters can be confusing to drivers.

“They're using a round knob that sits right next to the round knobs that are on your heat and air conditioning controls,” Kane said. “When controllers are located in places that we don't expect, or they're different, it's well known that drivers are going to make errors.”

But in cases where drivers note that they shifted their vehicles into park, there is speculation that an underlying technological issues could be to blame, an issue that Kane called “very complex” and believes isn’t receiving the scrutiny it deserves as the manufacturer and federal investigators focus on human error.

The investigation will specifically target Dodge Rams from the 2013 to 2016 model years and Durangos from 2014 to 2016. For now, there is no accompanying recall as the agency seeks to determine the cause for the issue.

ABC News' Daniel Steinberger and Erin Dooley contributed to this report.