Nearly a year after signing record labor contracts with the United Auto Workers (UAW), two of the Big Three automakers find themselves dealing with the possibility of more strikes.

The latest move by the UAW comes after the labor union said on Wednesday that members at Ford’s (F) tool and die unit at its Dearborn Rouge complex will go on strike on Sept. 26 if local contract issues are not resolved.

On top of the four-year contract that the UAW signed with Ford, there are local laws and regulations that Ford must comply with in order to complete a deal. Over a year has passed since the past contract expired, the union said, and Ford hasn’t struck a deal on those local issues. Those include job security and wage parity for skilled trade workers, as well as other work rules that need to be hammered out, the union said.

A Ford spokesperson did not immediately respond when reached by Yahoo Finance for comment, but the automaker told Reuters that it has “been at the table problem-solving” as “negotiations continue and we look forward to reaching an agreement with UAW Local 600 at Dearborn Tool & Die.”

Disruption at Ford's Rouge complex would be deeply problematic for Ford, largely because the highly profitable F-150 pickup is assembled there. A source tells Yahoo Finance that there is an "understanding" among UAW members about respecting picket lines, meaning if Local 600 strikes, other UAW members at Rouge could strike as well.

The situation between the UAW and Stellantis (STLA), which makes vehicles such as Ram Trucks, is much more contentious.

In a fiery address earlier this week, UAW president Shawn Fain said Stellantis violated its agreements in reopening its closed Belvidere, Ill., site. Projects at Belvidere like an auto parts hub in 2024, a stamping plant next year, and an assembly plant in 2027 are all in limbo as a result, Fain said.

Fain also said Stellantis was planning to move Dodge Durango SUV production from Detroit to a plant in Canada.

“We’re preparing to take action at Stellantis to enforce our contract and make this company keep its promises they made to the American people," Fain said.

The UAW is convening its Stellantis Council to decide on next steps and will be holding strike authorization votes at a handful of Stellantis local chapters. Union officials said several local chapters are currently eligible to take strike authorization votes under a grievance procedure as outlined in the current labor contract. But no dates have been publicly announced yet.

Union officials also tell Yahoo Finance that the vast majority of Stellantis local chapters are working through the grievance procedure—and are already or will soon be eligible to take strike authorization votes.