The use of a chassis dynamometer for inspection maintenance and drive train fault diagnosis has been developed for urban transit buses.Transit bus maintenance management has long sought a means to optimize bus preventive maintenance intervals. Historically, transit bus preventive maintenance has been scheduled with either time or mileage as the controlling parameter. This paper provides a basis for implementing vehicle dynamic testing that can substantially reduce the costs and manpower associated with preventive maintenance inspections and repairs.By subjecting the whole bus to the appropriate repeatable test conditions, certain measurements can be made to ascertain system parameters which can then be compared to established standards to indicate deteriorating conditions and diagnose defects. Dynamic inspection on a chassis dynamometer reduces to practice the maintenance principle, “if it works, don't fix it.”This paper will present the test procedures and equipment specifications that have been used. The integration of the dynamic test program into the preventive maintenance plan is explained and baseline test data for urban transit buses has been developed.