Workers at Fiat Chrysler approved a new labor contract on Wednesday that includes a $9,000 signing bonus, completing a volatile season of contract negotiations among Detroit's "Big Three."

The United Auto Workers announced that the 2019 collective bargaining agreement won 71 percent of the vote.

Besides the signing bonus, the agreement includes wage increases, a commitment of $4.5 billion in new plant investment, a pathway to permanent work status for temporary workers and limits on out-of-pocket health care costs, the UAW said.

Ford and General Motors have already ratified their accords with the union -- GM only after a paralyzing 40-day strike.

"It is not easy in pattern bargaining to be the final Detroit 3 contract," UAW President Rory Gamble said in a statement.

Workers at Fiat Chrysler approved a new labor contract that includes a $9,000 signing bonus, completing a volatile season of contract negotiations among Detroit's "Big Three
Workers at Fiat Chrysler approved a new labor contract that includes a $9,000 signing bonus, completing a volatile season of contract negotiations among Detroit's "Big Three AFP / Miguel MEDINA

"It means a much longer period of negotiating. Our negotiating team at the UAW and those local national negotiators were able to keep pattern and consequently negotiate a contract that will lift many lives during the life cycle of this contract."

Besides the strike, the UAW talks have also been shadowed by a mushrooming corruption scandal involving the union that saw Gamble ascend to the presidency after former President Gary Jones resigned.

The corruption allegations are also at the heart of a federal lawsuit GM filed earlier this month against Fiat Chrysler.

The suit alleged that FCA had bribed union officials to secure an unfair advantage in labor talks and to force it to agree to a merger.

The Italian-American automaker in turn accused GM of attempting to foil its planned merger with French carmaker PSA.

Chrysler