NHTSA Upgrades Probe Into GM Brake System for 1.1 Million Vehicles

The National Highway Traffic Safety Administration (NHTSA) has upgraded its investigation into General Motors' eBoost brake-by-wire system to an engineering analysis, the agency's highest level of probe. The federal regulator expanded the scope of the investigation on August 21, increasing the number of affected vehicles from 3,300 to more than 1.1 million.

The probe follows reports of between 221 and 227 incidents, including 21 to 22 crashes or fires and at least six injuries. Affected models include the Cadillac Lyriq, Chevrolet Blazer EV, Equinox EV, Colorado, GMC Canyon, and Buick Enclave and Envision, as well as the Honda Prologue and Acura ZDX developed through a joint venture.

A conflict has emerged between the automaker and the regulator regarding the nature of the failure. While General Motors attributed the issues to spindle fractures that it claims do not disable critical safety functions until a vehicle stops, the NHTSA's Office of Defects Investigation found reports of immediate loss of brake assist during active braking. General Motors maintains that the condition does not present an unreasonable safety risk but has pledged to cooperate with the engineering analysis, which is the final step before a potential mandatory recall.