The U.S. National Highway Traffic Safety Administration (NHTSA) started investigating Chrysler regarding its slow recall process on its Dodge Ram pickup trucks that have potential steering issues.

In November 2013, Chrysler announced that it will issue three separate recalls for a total of 1.2 million Ram pickup trucks due to a possible defective steering system. The recall includes 706,664 2003-2008 Dodge Ram 2500 4x4 and 3500 4x4, 2007-2008 Dodge Ram 3500 4x2 Cab Chassis and 2006-2008 Dodge Ram 1500 Mega Cab 4x4.

The second recall covers 265,057 2008-2012 Ram 2500 4X4 and 3500 4X4 trucks, 2008-2012 Dodge Ram 3500 4x2 Cab Chassis, and 2008 Dodge RAM 1500 Mega Cab 4x4. The announcement includes vehicles sold in the United States, Canada, Mexico and overseas, and a replacement will be free of charge. Work on the affected vehicles will begin in January of this year.

But on Monday, federal investigators posted documents online showing that Chrysler is being investigated because of the slow progress and poor communication. Customers complained that the automaker told them that it might take months before they can get replacements for their defective steering systems. Chrysler quickly denied the allegation and clarified that it has been cooperative with the federal agency auditing process, according to Reuters.

"Customers have been advised in accordance with the regulations governing recalls," Chrysler spokesman Eric Mayne said in an email statement. "We are continually replenishing our supply of replacement parts. Chrysler Group regrets any inconvenience our customers may have experienced."

The recalls of the pickup trucks have been temporarily suspended while the NHTSA investigates the issue.

Chrysler is aware of the six accidents and two injuries involving the recalled models, but the replacement parts will not be available until late 2014, Detroit News reported.

The NHTSA gave Chrysler until Nov. 21 to respond to inquiries related to the recall process and complaints from the customers.