Officials with Unifor Local 200 and Nemak are sitting down this week in talks over the plant's planned closure in Windsor next year.
Talks started Wednesday and are expected to continue on Friday.
The company announced last summer it intended to shut down the Windsor facility in the middle of 2020.
Unifor fought back with a blockade that lasted almost two weeks. It accused the company of violating a collective agreement with the workers, who had agreed to take a pay cut to keep the plant open until 2022.
The Ontario Labour Relations Board and a Windsor judge ordered the union to stop the blockade, but the union refused. Eventually it relented when Nemak agreed to new talks, and an expedited arbitration process should the negotiations fail.