I describe the first stages of a process of design research in which I employ problem-based learning in a course in engineering ethics, which fulfills a requirement for students in engineering degree programs. The aim of the course is to foster development of particular cognitive skills contributing to moral imagination, a capacity to notice, respond to, and think about basic values in open-ended problem situations. In the course, groups of students develop their own problem situations based on their experience and expertise in engineering practice, then respond to those situations through a guided process of inquiry and problem solving designed to focus their attention on basic ethical values. I close with observations on the process of designing the course, laying the groundwork for subsequent formal assessment.