DETROIT (Reuters) - U.S. safety regulators are investigating Ford Motor Co's F.N Fusion and Mercury Milan sedans from the 2007 to 2009 model years for brakes that may fail in certain conditions, the National Highway Traffic Safety Administration said on Tuesday.

A Ford logo is pictured at a car dealership in Monterrey, Mexico, November 9, 2016. Picture taken November 9, 2016. REUTERS/Daniel Becerril

There have been three reported crashes related to this issue, but no injuries, NHTSA and Ford officials said.

The probe was opened on Dec. 20 and involves one of Ford’s most popular models, the Fusion. The Milan is no longer produced.

The probe can lead to a safety recall but is short of one at this point.

A report on the NHTSA website showed that when the sedans go over rough or uneven surfaces, such as a manhole cover, or on slippery roads, the anti-lock braking system may not work properly. This can increase the distance required to stop the cars, heightening the chance of a crash.

NHTSA said that in some cases, consumers complained that the brake pedal “goes soft” and often is reported as “going to the floor.” Also, drivers have said their cars have ended up in the flow of traffic when the vehicles did not stop as expected, such as at traffic signals.

Ford said it is cooperating with federal safety officials in the investigation.

The Fusion and Milan from these model years have been involved in several past recalls. The 2006-2011 Fusion and Milan sedans are among the 1.9 million Ford models affected by an ongoing massive Takata Corp 7312.T air bag recall that includes more than a dozen automakers.

In addition, 2010 and 2011 Fusion and Milan models were recalled for fuel tanks that may crack.

(This version of the story corrects headline, first paragraph to show model years of recalled cars was 2007-2009, not 2009-2011)