Electronics are rapidly expanding in the diesel on-highway truck market and will soon represent the dominant technology for heavy-duty diesel engine fuel control. The strategy choices for the diesel engine manufacturer required to meet legislated exhaust emissions, while offering competitive fuel economy, all point toward electronic fuel injection control. The industry's transition to electronic fuel injection systems was initiated with the introduction of the Detroit Diesel Electronic Control system (DDEC) in 1985. This introduction precipitated the tremendous learning curve in the application of electronics to the heavy-duty truck market for both the engine manufacturer and the vehicle builder. This has been an on-going process as the vehicle builder's production line mix completes the transition from mechanically controlled to electronically controlled diesel engines.This paper provides an overview of the DDEC system, discusses the infrastructure developed to support the DDEC system, and relates experiences with DDEC in the truck and bus market.