During Preliminary Evaluation (PE11-013), the Office of Defects Investigation (ODI) conducted an analysis of consumer field data from its Vehicle Owner Questionnaire (VOQ) database and from complaint data submitted to ODI by Chrysler. ODI's analysis of VOQ data identified 13 complaints alleging failure of either the right or left rear lower control arm due to excessive corrosion.All of these complaints were associated with vehicles originally sold or registered in a "salt belt" state (for the purposes of this investigation, 'salt belt' includes Connecticut, Delaware, Illinois, Indiana, Iowa, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, Ohio, Pennsylvania, Rhode Island, Vermont, West Virginia, Wisconsin and the District of Columbia).All of the complaints were associated with vehicles manufactured in model years (MY) 2004 or 2005. Three of these complaints also allege a loss of vehicle control due to the rear lower control arm failure. No complaints related to the alleged defect were identified on vehicles manufactured during MYs 2002 or 2003. Similarly an analysis of Chrysler complaint data identified 11 complaints (2 of which are duplicative of VOQs) alleging failure of a rear lower control arm due to excessive corrosion.All 11 of these complaints were from consumers operating vehicles in a "salt belt" state and vehicles manufactured in either MY 2004 or 2005. Three of these complaints (not duplicative of VOQs) also allege a loss of vehicle control due to the rear lower control arm failure.The original scope of PE11-013 included MY 2002 through 2005 Jeep Liberty vehicles as they were in the same generation.In response to an Information Request (IR) letter sent by ODI, Chrysler provided information and sample components identifying a substantial design change of the rear lower control arms after MY 2003 and beginning with MY 2004.Analysis of complaint data from both data sources (ODI and Chrysler) did not identify any applicable complaints (lower control arm failures due to excessive corrosion) from vehicles manufactured during MY 2002 or 2003.Similarly no complaints from either data source were found in states outside of those identified as "salt belt" states.Chrysler stated in its IR letter response that its investigation and analysis is ongoing to determine the scope, possible root causes of the unusual lower control arm corrosion, and define possible consequences to motor vehicle safety. Based on ODI's data analysis from both sources (ODI and Chrysler data), this investigation has been upgraded to an Engineering Analysis (EA11-013) focused on vehicles originally sold or registered in a "salt belt" state and produced during MY 2004 and 2005, to further assess the scope and potential safety consequences of the alleged defect.