The company says it will change or replace the keys on the cars from the 2000 to 2014 model years.
Like the earlier recalls, GM says the switches can unexpectedly move out of the "run" position if the cars are jarred, such as by going over railroad tracks or a pothole. That can shut off the engines and disable power steering.
GM recalled 2.6 million older small cars earlier this year for a similar problem.
According to WDIV, the model/years being recalled are: 2005-9 Buick Lacrosse, 2006-14 Chevrolet Impala, 2000-5 Cadillac Deville, 2004-11 Cadillac DTS, 2006-11 Buick Lucerne, 2004-5 Buick Regal LS & GS, and 2006-8 Chevy Monte Carlo.