A system and method for guiding an off-highway truck along a roadway with respect to a trolley line determine a position of the off-highway truck on the roadway by sensing two or more roadside objects and uses the determined position of the off-highway truck and a known position of the trolley line relative to the two or more roadside objects to automatically determine a relative position of the off-highway truck under the trolley line. Based on the relative position of the off-highway truck under the trolley line, the off-highway truck is automatically steered to alter the position of the off-highway truck relative to the trolley line, e.g., to maintain an electrical power flow from the trolley line to the off-highway truck.