NEW YORK (CNN) -
A federal investigation into cruise-control problems is underway in an estimated 3.7 million Ford F-150s, Ford Expeditions and Lincoln Navigators, auto safety regulators said Wednesday.
The possible defect in cruise-control mechanisms can cause a vehicle to catch on fire when the engine is off. The National Highway Traffic Safety Administration said it's looking at 1995-1999 and 2001-2002 F-150s and 1997-1999 and 2001-2002 Expeditions and Navigators.
A federal investigation into the same defect in the 2000 model year of the vehicles recently ended, with the NHTSA saying the problems with those automobiles were adequately dealt with by a Ford recall.
Ford recalled the 2000 vehicles on Jan. 27.
In the most recent investigation, at least 218 problems have been reported involving cruise control deactivation switch failures and related engine-compartment fires, the agency said.
NHTSA spokesman Rae Tyson said there were no injuries or deaths reported due to the problems.
But in a report on the problems, the agency's investigation office said it "has identified other reports of 'key off' engine-compartment fires in Ford vehicles with similar speed-control deactivation switches (SCDS) that were not the subject of this preliminary evaluation or Ford's recall."
By expanding the investigation, the report says, "we will optimize our ability to identify the problem's root cause. Once identified, we will better understand the SCDS failure frequency and why engine compartment fire rates in other Ford vehicles are markedly lower."
A Ford spokeswoman, Kristin Kinely, said, "Our position hasn't changed. We are working closely and will continue to cooperate with the government and the investigation until it is closed."
A government investigation of vehicles begins with a preliminary evaluation, the fact-finding phase. If the facts justify it, the investigation moves to a engineering analysis, the testing phase. If a defect is found the next step is a recall. Approximately 60 percent of investigations that reach the engineering analysis level result in recalls.
The expanded defect investigation is being opened at the engineering analysis level because NHTSA found enough evidence to support doing so when it was investigating the 2000 model years.
Ford (down $0.18 to $10.99, Research) shares fell about 1 percent in afternoon New York Stock Exchange trading.
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-- from CNN Correspondent Julie Vallese