The downshift would “cause unexpected rapid vehicle deceleration” with some drivers saying that the truck’s rear wheels would temporarily lock, seize and/or skid, causing them to potentially lose control and increase the risk of an accident. The investigation could affect 1.3 million trucks.

Federal safety regulators have launched an investigation into nearly 1.3 million Ford F-150 pickup trucks following reports of uncommanded downshifts that may cause abrupt deceleration and temporary loss of vehicle control.

Federal safety officials have opened an investigation into nearly 1.3 million Ford F-150 pickup trucks after drivers reported sudden downshifts at highway speeds that, in some cases, caused the rear wheels to lock up.