As 42 million Americans prepare to hit the road for Memorial Day weekend, Fiat Chrysler just announced it is recalling 4.8 million vehicles over a defect that could prevent drivers from deactivating cruise control and warned owners not to use the function until they get software upgrades.

The Italian-American automaker said no injuries or crashes are related to the large recall campaign but said it had one report of a driver of a 2017 Dodge Journey unable to deactivate the cruise control.

Fiat Chrysler, which in 2015 was hit with penalties from U.S. regulators totalling $175 million for safety lapses, did not say how much the recalls would cost.

The recall addresses what Fiat Chrysler called an "unlikely sequence of events" that could lead to drivers being unable to cancel cruise control. The company emphasized drivers could overpower the system by continuously applying the brakes until the vehicle stopped or the vehicle could be stopped by shifting into neutral and braking.

Fiat Chrysler noted that at times cruise control systems automatically initiate acceleration to help vehicles maintain driver-selected speeds, including when going up an incline. If an acceleration occurs simultaneously with a short-circuit in a specific electrical network, a driver could be unable to deactivate cruise-control.

Fiat Chrysler said vehicles may be placed in park once stopped, at which point cruise-control is canceled.

The recall involves a group of gasoline-powered vehicles with automatic transmissions from various model years built from 2014 through the 2019 model year. Most of the vehicles being recalled cover 2014-2018 model years.

Among the vehicles being recalled are the Chrysler 200, Chrysler 300, Chrysler Pacifica, Dodge Charger, Dodge Challenger, Dodge Journey, Dodge Durango, Jeep Cherokee, Jeep Grand Cherokee, Jeep Wrangler and Ram 1500, 2500 and 3500 pickup trucks and Ram 3500/4500/5500 cab chassis trucks.

Fiat Chrysler made the announcement on the first day of the busy Memorial Day weekend, which traditionally kicks off the summer driving season. The company said it is recalling an unspecified number of additional vehicles in Canada, Mexico and other markets, and recalling some Fiat Fremont vehicles built on the same platform of the Dodge Journey. The company said it was also warning owners in other markets not to use cruise control until recalls are completed.

Fiat Chrysler said it uncovered the issue through tests its engineers had conducted.

"Notwithstanding the extraordinary circumstances that must exist before a customer would experience a problem, we are taking this action because we are fully committed to vehicle safety," Mark Chernoby, Fiat Chrysler's chief technical compliance officer, said in a statement.

"We have a remedy and a widespread network of engaged dealers who are preparing to deliver service... We urge customers to follow the instructions on their recall notices."

Fiat Chrysler noted the recall repairs are free of charge and said it will begin alerting affected customers as early as next week. The recalled vehicles have collectively been driven more than 200 billion miles.

Fiat Chrysler has vowed to improve safety procedures after the National Highway Traffic Safety Administration in 2015 imposed $175 million in civil penalties for safety lapses.

In July 2015, Fiat Chrysler agreed to a $105 million settlement for mishandling nearly two dozen recall campaigns covering 11 million vehicles. It agreed to a three-year consent agreement and monitoring by former Transportation Secretary Rodney Slater. It was separately fined $70 million by U.S. regulators in 2015 for failing to report vehicle crash deaths and injuries since 2003.

In 2015, Fiat Chrysler booked a 602 million-euro ($705 million) after-tax charge, mainly for estimated future recall costs.