ON-BOARD DIAGNOSTICS FOR EMISSION CONTROL SYSTEMS

The introduction of Electronic Controls on engines in the late 1970's brought about many changes in the auto industry. One major change was the inclusion of a sophisticated diagnostic system, resident in the controller that allowed it to monitor itself and the system it controls. General Motors introduced On-Board Diagnostics on all of its closed-loop fuel control systems in 1980 and has continued to enhance and refine the diagnostic system each succeeding year. This paper presents a brief history of On-Board Diagnostics, the strategy behind the diagnostics and the benefits of diagnostics to maintaining control of vehicle emissions and aiding in the service process.