Complaints About GM Brakes Mount: The government's auto safety agency has added the GMC Suburban to its investigation into complaints of malfunctioning anti-lock brakes on some GM pickups and sport-utility vehicles. That brings to 7,350 the total number of complaints about General Motors Corp. vehicles' anti-lock brakes--the largest number for any investigation now open under the National Highway Traffic Safety Administration. The GM vehicles undergoing engineering analysis--an upgraded investigation to determine if parts are defective--are GMC Suburban sport-utility vehicles, Chevy S-10 pickups, Chevy Blazer sport-utility vehicles, GMC S-15/Sonoma pickups, GMC Jimmy sport-utility vehicles and Oldsmobile Bravada sport-utility vehicles. Motorists have reported more than 2,000 accidents and 570 injuries involving the vehicles. More than 2.2 million of the vehicles are on the road.