Ford stopped making and shipping the F-150 Lightning because of a problem with the batteries.

Ford Motor Co. found the problem during pre-delivery inspections of the F-150 Lightning electric pickup and has stopped making and sending them out.

In an email, Ford spokeswoman Emma Bergg said, “We are not aware of any cases of this problem in the field.” She said that the order to stop making things came out at the beginning of last week.

Ford said it was looking into the situation, which CNBC and Motor Authority had already talked about. In afternoon trading, the automaker’s stock fell 1%.

No timetable for starting up again was given.

Ford obtains batteries from the South Korean company SK Innovation Co Ltd., SK On, which has a battery division.

“We are looking into the situation right now,” an SK On official said in a statement.

South Korea, China, Hungary, and the United States are all places where SK On makes batteries for Ford, Volkswagen AG, Hyundai Motor Co., and other clients.

On Wednesday morning, shares of SK Innovation, the company that owns SK On, fell as much as 3.9% and came close to hitting a three-week low.

Ford reported bad quarterly results earlier this month and said that the supply of semiconductor chips might not be stable.

Last year, the company that makes electric vehicles (EVs) made a third work crew for the electric pickup truck to meet the high demand for EVs.