By The Associated PressTHE VEHICLE: About 623,000 Dodge Caravan and Chrysler Town and Country minivans in the U.S. from the 2005 and early 2006 model years. THE PROBLEM: In September of 2011, the National Highway Traffic Safety Administration began investigating complaints that the headlights could go dark while the vans were being driven. The problem was traced to the headlight switch, where friction between metal and plastic parts can cause bits of plastic to fall onto an electrical contact, causing the lights to fail. In some cases the headlights wouldn't come on or could not be shut off. The problem, which worsens as the minivans age, can normally be fixed by turning the lights on and off. Chrysler applied a lubricant to newer minivans, which have far fewer problems. THE IMPACT: Chrysler and NHTSA received 919 complaints from drivers about the problem. One driver whose headlights failed hit a deer and another suffered a minor injury after driving into a ditch. THE SOLUTION: Chrysler will offer a lifetime guarantee on the switches and will replace them at no charge when people start to have problems. The company will begin notifying owners early next year. NHTSA said it closed the investigation without a recall because the problem can be fixed by switching the lights on and off, and because of Chrysler's extended warranty. The probe was closed on Nov. 29 and the decision was made public on Thursday.