A long line of unsold 2021 Silverado pickup trucks sits at a Chevrolet dealership Sunday, Feb. 21, 2021, in Englewood, Colo. …
FILE - Several 2021 Silverado pickup trucks sit at a Chevrolet dealership in Englewood, Colorado, Feb. 21, 2021.

The U.S. National Highway Traffic Safety Administration (NHTSA) said Tuesday it is investigating complaints of airbags failing to deploy in late-model General Motors vehicles, mostly full-size pickup trucks and sport utility vehicles.

The NHTSA said the investigation would include nearly 750,000 Chevrolet, Cadillac and GMC vehicles from the 2020 and 2021 model years.

In documents posted to the agency's website, the NHTSA outlined 15 complaints regarding alleged airbag malfunctions. The documents indicated that six of those complaints involved crashes consisting of a total of eight injuries and significant front-end collision damage to the vehicles.

The agency said its Office of Defects Investigation is looking into the complaints to determine the scope of the problem and safety issues involved.

The NHTSA said GM issued a service bulletin to dealers about the problem in March, but there has not been a recall. The GM bulletin said rust particles can accumulate on a driver's air bag connection terminal. That can cause the air bag malfunction light to come on and could prevent the air bags from inflating.

The probe covers Chevrolet Silverado and GMC Sierra pickups, as well as Chevy Tahoe and Suburban SUVs. Also included are GMC Yukon and Cadillac Escalade SUVs, and the Cadillac CT4 and CT5 sedans and XT4 SUVs.