DETROIT — About 2,500 workers at a Canadian General Motors plant that makes the Chevrolet Equinox SUV are on strike in a dispute over job security.

Members of Unifor Local 88 in Ingersoll, Ontario, west of Toronto, stopped working when their contract expired at 10:59 p.m. Sunday.

The strike couldn’t come at a worse time for GM. A new version of the Equinox compact SUV just started to hit dealerships during the summer, attracting buyers in the hottest part of the U.S. auto market.

The union says GM won’t designate the factory as lead producer of the Equinox. GM moved production of the GMC Terrain, which is similar to the Equinox, to Mexico in July, and 600 workers were laid off. The Equinox also is made in Mexico and workers fear more jobs could go south.