Prius Traction Control Complaints on the Rise Toyota Can't Get a Grip on the Problem Toyota is unable to modify the troublesome Prius traction control system without placing the vehicle's sophisticated hybrid drive system in jeopardy, according to a Toyota service technician familiar with the Prius problem. In a mountainous or snowy areas, the little car can be more than just difficult, Prius owners complain. "I live in the mountains, up steep hills and dirt roads. I consider the slippage problem with the shutting down of power to the wheels just when you need more not less traction to be a very serious problem and a potentially life-threatening design flaw," a New England Prius owner told ConsumerAffairs.Com. Read more.