The continuing trend in technological advances has led to the implementation of complex systems in order to meet demands for improved services and products. Such implementation attempts to perform on-going activities in an effective and efficient manner. The size and complexity of these complex systems can be witnessed by the transportation systems, the highway systems, and the medium and heavy duty vehicles systems (engine, transmission, and brakes) which rely on electronic controls and require a combination of hardware (off-board diagnostic tools), software, and even peopleware.

In this thesis work, an investigation is made to study the impact of implementing electronic controls to medium and heavy duty vehicles systems on the shop floor procedure when maintenance is performed. The impact reflects a significant change in the diagnostic procedures. Several manufacturers, such as Cummins, Caterpillar, Detroit Diesel, and Rockwell, design their systems with different electronic control units. Once these different systems are assembled together as a single entity in a vehicle, different formats and procedures must be followed when performing diagnostic procedures. Because of the change of procedures, traditional offboard diagnostic tools have to be replaced by new tools to ensure quality diagnostic repairs, thus introducing the cost consideration to system analysis.

The main contribution of this thesis is to present a Systems Engineering Approach to integrate Medium and Heavy Duty Vehicles Electronic Controls (so the same off-board diagnostic tool can be used on all manufactured vehicles) and Shop Floor Procedures (human factors and quality control in maintenance). An intelligent off-board diagnostic tool will be designed and act as an expert system to aid the service technician(s) in performing diagnostic procedures. Consequently, a significant reduction of work time for repairing can be achieved for productivity improvement, and the retraining of the service technician(s) can also be realized. The results from this thesis work can effectively assist the top managers, service managers, and mechanics in performing diagnostic repairs, and can provide a mean for effective communications between the manufacturers, the repair facilities, and the customers.