According to recent reports, GM was aware of ignition switch problems that affected 6.7 million cars for 11 years. Despite this, they failed to warn customers about the issues and recall the vehicles until just last month.

Documents that were released on Friday, show that, yet again, the car company was late in warning customers about the problem. The documents also expose patterns of ignition switch problems, some dating back to 1997. In fact, GM has recalled a total of 29 million vehicles just this year.

The problem essentially means that ignition switches can go out of “run” position, turning off the engine and power steering and brakes. Drivers can then lose control of their car, and air bags will not function properly in the case of an accident. These issues have been blamed for at least 13 deaths.

The ignition switches are more prone to switching off if the driver’s keys have a lot of weight on them and the car goes over a bump. GM says that a dealership in Michigan reported a complaint back in 2003 from a customer saying that their car was stalling. This particular customer had around 50 keys and a set of brass knuckles on his key ring. Following this complaint GM issued a service bulletin to dealers warning of the problem, but did not recall any vehicles at that time.

Later in 2003 GM made the ignition switch harder to turn on in the Malibu, but did not issue a recall. In 2004, the part was fixed in the Grand Prix but the part number was not changed.

The cars being recalled  are mostly mid-sized and large cars, including the 2000-2005 Chevrolet Impala and Monte Carlo, the 1997-2005 Chevrolet Malibu, the 1999-2004 Oldsmobile Alero, the 1998-2002 Oldsmobile Intrigue, the 1999-2005 Pontiac Grand Am and the 2004-2008 Pontiac Grand Prix. All of these vehicles use the same ignition switches.