Volkswagen was in hot water for the same earlier this year.
The Justice Department filed suit against Fiat-Chrysler, alleging they used special software to get around the tests.
Fiat-Chrysler denies wrongdoing.
During a rollover, side airbags and seatbelts may not work properly due to a defect in the truck’s software so far blamed for one death.
The vehicles being recalled are the 2013-16 Ram 1500 and 2500 pickups, and the 2014-16 Ram 3500.
Fiat Chrysler said the recall covered 1m vehicles in the United States and 300k trucks in Canada, Mexico and elsewhere.
The company recently recalled 1.4m Jeep, Dodge, and Chrysler vehicles due to infotainment (remote) hacking. The new recall is a different problem, and doesn’t have to do with remote hacking, according to Fiat Chrysler.