U.S. safety regulators are investigating complaints that the power brake assist can fail on some Ford F-150 pickup trucks.
The National Highway Traffic Safety Administration says the probe covers about 250,000 pickups from 2011 and 2012 with 3.5-liter six-cylinder engines.
The agency says it has 32 complaints alleging that electric vacuum assist pumps can fail, causing loss of power brakes and increased braking effort. Two crashes were reported but no injuries.
In all the complaints, no warnings were issued. The agency says the complaints are increasing. About 60 percent coming in the past nine months.
Investigators will look into the cause of the problem and how often it happens. The probe could lead to a recall.
Ford says it's cooperating. Customers with problems should contact their dealer.
