(Reuters) -General Motors is pausing production at a pickup-truck plant in Mexico for several weeks, crimping output of its top-selling vehicles, people familiar with the situation told Reuters, and the company confirmed the information when asked. 

GM's assembly complex in Silao, Mexico, where the company builds the Chevrolet Silverado and GMC Sierra pickups, was down for the first two weeks of July, and is scheduled to be idled again the weeks of August 4 and 11, two people familiar with the matter said. GM did not confirm the precise schedule.

"Scheduled down weeks at GM Silao are part of a standard operating process focused on optimizing production at our manufacturing complex," GM said in response to a Reuters inquiry. 

The Silverado and mechanically similar Sierra are by far GM's top sellers in the U.S., and major profit generators. GM also builds the Silverado and Sierra at factories in Fort Wayne, Indiana; Flint, Michigan and Ontario, Canada. 

It is common for automakers to halt factory work to perform maintenance or adjust assembly lines for model changes. Most of GM's U.S. factories were not operating last week as part of a usual down week for the July Fourth holiday.

Still, several weeks of downtime is unusual for a factory that makes GM's most popular models. Pickups are the biggest money makers for GM, Ford and Ram-maker Stellantis, and their truck plants often run around the clock.

GM sold 278,599 Silverado trucks in the first half of 2025, a 2% increase from the year-ago period. The automaker sold 166,409 Sierra trucks in the same timeframe, a 12% increase from the first half of 2024. 

U.S. President Donald Trump's trade war has disrupted supply chains and factory work for automakers and parts suppliers in recent months. 

Some car companies have shifted production plans to mitigate the impact of Trump's tariffs on imported cars. China's retaliatory restrictions on magnets and other parts that include rare-earth metals - used broadly in car components - also have scrambled operations.