Polyurethane foam has been used in European vehicle applications as a covering for wiring harness assemblies for over a decade. During this period, the polyurethane chemistry has evolved to meet the stringent needs of the automotive engine compartment environment. This is a proven technology with many advantages over standard wire covering systems. In many cases, the improvements in environmental performance, part-to-part consistency, and aesthetics can be achieved while reducing part cost. 3-D molded wiring assemblies provide improved fit in vehicle installations. Yet, polyurethane foam over-molding technology is rarely utilized in North America for vehicle wiring applications.Polyurethane foam is also being used to cover electronic circuit assemblies in vehicular applications. As a further integration of component technologies, circuit assemblies are being built into wiring harnesses with the polyurethane foam being used as an environmental covering. This may be a cost effective alternative to traditional electronic module constructions.