(FOX 2) - UAW President Shawn Fain called on 7,000 Ford and General Motors union members to join the strike Friday.
Workers at Ford Chicago Assembly Plant and GM Lansing Delta Assembly walked to the picket line at noon.
Lansing Regional Stamping will continue working.
"Sadly, despite our willingness to bargain, Ford and GM have refused to make meaningful progress at the table," Fain said.
Last week, workers at all General Motors and Stellantis parts distribution facilities joined the strike.
Workers at 38 General Motors and Stellantis plants walked out at noon. They joined workers from three plants that started striking Sept. 15.
The union is participating in a stand-up strike, meaning that only some members are striking, but more will be added as negotiations continue.
Last week's strike addition included only Stellantis and GM employees because Fain said Ford's negotiations had made good progress.
"Both companies are still offering deficient cost of living adjustments that will provide zero increases over the next four years. Both have rejected job security proposals. Both have rejected profit-sharing proposals. And both companies have rejected our proposals to convert temps," he said.
The union initially was asking for a 46% pay raise, a 32-hour work week with 40 hours of pay, the tier system removed, and restoration of traditional pensions for new hires, among other demands. However, the union said it is now willing to accept a pay raise percentage in the mid-30s.