SAN ANTONIO—Toyota’s San Antonio plant is back on line after a three-month shutdown forced by the faltering economy and weak Tundra truck sales.

The Japanese automaker plans to add a second production shift in April to the first shift that returned Monday, but the shaky economy leaves that outlook in doubt. Analysts say tight credit markets and failing consumer confidence have kept people away from auto showrooms. Tundra sales are off 65 percent since last year, the largest drop among Toyota models.

“Fuel prices are certainly more positive than they were three months ago,” Jack Nerad, executive market analyst for Kelley Blue Book, said in Tuesday’s editions of the San Antonio Express-News. “But consumer confidence is very poor, and employment numbers are bleak right now—neither of which look good for the industry.”

Uncertain expansion plans didn’t dampen the enthusiasm of workers who were just glad Toyota’s first shutdown of a U.S. plant was over. Some 2,000 employees scrambled over the assembly line, fitting new trucks with parts and inspecting those ready to leave the plant. They completed the first 2009 Tundra just minutes after the 6:30 a.m. production start.

“Hear that noise right now?” asked team leader Malvin Henry, pointing to a conveyor overhead carrying a Tundra cab to the line. “It sounds good. It means we’re back to work.”

Henry and others weren’t out of work during the shutdown. Since August, they’ve been working on process improvements, and about 1,000 of them were implemented by the end of the downtime.