The development of modular product families provides a way to reduce the total products cost. Costs forecasts in the early stages of product development support the development and selection of modular product structure concepts. In this paper a case study for predicting the costs of harness variants is shown. Next, according to the results of the case study, an approach for costs forecast by the identification and determination of the effects of complexity costs elements is presented. This approach represents an extension of the Integrated PKT-Approach for the development of modular product families.
