CAMI Ingersoll workers hit the picket lines Sunday night after a strike deadline of 11 p.m. came and went.
The 2,500 members of Unifor local 88 walked out Sunday at 10:59 p.m. as the two sides failed to reach agreements on plant operations, economic issues, and especially job security.
Local 88 president Dan Borthwick said the union is pushing to have the plant designated the lead producer of GM's Chevrolet Equinox to ensure jobs aren't shifted to Mexico.
He said the issue has become more pressing after GM shifted production of its Terrain small SUV from the plant to Mexico earlier this year at a loss of more than 400 jobs.
"We're done with that. We need some job security and commitment," said Borthwick.
"GM just has to get around their corporate greed. They need to start sharing the $12 billion they make a year."
The company said in a statement that it's disappointed the two sides couldn't reach a deal, but that both sides have made progress on several issues over recent weeks.
GM said it committed $800 million in 2015 to prepare the CAMI plant for the latest Equinox model, but with some production of the vehicle already happening in Mexico, Borthwick said he wasn't reassured by the investment.
"The $800 million was spent when the Terrain was here, so there's no guarantees."
The shifting of work to Mexico is a key issue for the ongoing North American Free Trade Agreement negotiations, and creates significant complications for auto maker labour negotiations, said Brendan Sweeney, project manager at McMaster University's Automotive Policy Research Centre.
"There's so much uncertainty. How can they make these commitments today when obviously NAFTA is being renegotiated. I don't know how they can do that; they're kind of hamstrung."
Sweeney said GM and other auto makers were able to reach contract agreements last year, with Unifor securing large investments from GM in its Canadian operations including its assembly plant in Oshawa, Ont.
But workers at the CAMI plant operate under a different contract from other GM employees, and their renewal negotiations have come at a tricky time as auto makers face uncertainty on key policies like how many cars they'll be able to import to the U.S. from Canada and Mexico, and whether those vehicles will face tariffs.
"Any movement one way or another on those issues will impact what companies do. But the companies won't do that stuff until they know. So it's just crappy timing to be bargaining," said Sweeney.
Borthwick at local 88 said he's confident the two sides can reach an agreement despite NAFTA, but that union members are prepared to hold out for progress on the key issues.
"We're going to hold strong until we achieve our goals."