U.S. safety investigators have launched a new review of steering complaints in Dodge Ram pickup trucks that could result in a bigger recall of that vehicle, documents showed on Friday.

The National Highway Traffic Safety Administration last December recalled 22,274 4500- and 5500-series pickups made by Chrysler between 2008 and 2011 for misaligned steering components.

Investigators said the suspected defect in the medium-duty trucks could cause certain steering rod parts to weaken and possibly break.

NHTSA said in a defect notice that it had opened a preliminary investigation of 2500- and 3500-series Ram trucks for the same model years based on 12 new motorist complaints alleging similar problems.

The new investigation could effect as many as 160,000 vehicles.

A preliminary investigation is often the first step toward a recall. NHTSA has not yet said whether a recall will occur in this case.

Ram trucks, a signature Chrysler product, registered a 24 percent jump in sales in March compared to the same period a year ago.

A second recall of Ram trucks last year centered on potential axle problems in 56,000 vehicles.

Chrysler is a unit of Italy’s Fiat.