NHTSA, the government's road safety agency, has pressured automaker General Motors to recall nearly 3.8 million big pickup trucks and SUVs in the U.S and Canada to fix a brake problem.

The recall covers the Chevrolet Silverado and GMC Sierra 1500, 2500 and 3500 pickups from the 2014 through 2018 model years. It also includes the Cadillac Escalade from 2015 to 2017, and the GMC Yukon and Chevy Suburban and Tahoe from 2015 through 2018.

The pump in the power-assist brakes can put out less vacuum power than needed as it ages, which can lengthen stopping distances and increase the risk of a crash.

GM says the problems occur rarely and mostly occur at slower speeds using in parking lots.

3.46 million of the affected vehicles are in the U.S; the others are part of an early recall in Canada.

GM says dealers will recalibrate the electronic brake control module at no cost to customers.

Owners were expected to be notified starting September 6.

CHECK YOUR TRUCK | GM Recall website