DETROIT -- Two Ford Motor Co. (F) models are under investigation by U.S. safety regulators for problems similar to those that have caused nearly 3 million other Ford vehicles to be recalled.

The probes cover about 643,000 vehicles including 380,000 Edge SUVs from the 2011 to 2013 model years, and nearly 263,000 Fusions from the 2010 model year. In each case, other Ford vehicles have been recalled for what appears to be the same problems.

About 1,560 people have complained to the National Highway Traffic Safety Administration that the “door ajar” warning light won’t shut off on the Edges, and some have reported that the doors can fly open while the SUVs are moving. One injury was reported. The problem is similar to one that has dogged Ford for the past year, forcing it to recall 2.4 million other vehicles.

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In the other case, NHTSA said it has 547 complaints that the electric power-assisted steering can fail on the 2010 Ford Fusion. Last year, the company recalled Fusions from the 2011 and 2012 model years, but did not recall the 2010 models even though they have the same power steering system, the safety agency said in documents posted Monday. NHTSA said it has 12 reports of crashes and four injuries due to the problem.

The investigations could lead to expansion of the previous recalls, although that decision has not been made. The safety agency says it will “assess the scope, frequency and consequence” of the alleged defects.

Ford spokeswoman Elizabeth Weigandt said in a statement Monday that the company would cooperate in the investigations. “We continuously evaluate our processes for potential improvements, and when the data indicates a safety recall is needed, we move quickly on behalf of our customers,” the statement said.

But she did not answer repeated questions about why the vehicles that are under investigation weren’t included in the previous recalls or whether the Edges have the same door latches as those that were recalled earlier.

Shares of Ford Motor Co. edged up 3 cents to $12.10 in morning trading Monday. Ford shares are down more than 13 percent over the past year.