DETROIT (AP) — A government agency is investigating safety problems with two vehicles made by Chrysler, the Ram pickup truck and Jeep Grand Cherokee SUV.

The rear wheels can lock up in Rams from the 2009 and 2010 model years, potentially causing crashes, while power steering fluid hoses can leak in 2012 Grand Cherokees, possibly causing engine fires, according to documents posted Monday on the National Highway Traffic Safety Administration website.

The agency has received a dozen complaints from Ram owners about locking wheels, prompting the investigation that includes 230,000 pickups. Gears that allow the wheels to turn at different speeds can fail, causing the wheels to freeze while the trucks are moving, the agency said.