The Bus and Heavy Truck Industry is rapidly coming into the electronic age. Ancillary and convenience items are increasingly dependent on electronics for control and operation. Maintenance requirements for these systems have changed as they incorporate transistors in place of relays adding a new demand on the infrastructure in place to maintain these vehicles. Vehicle and product documentation includes circuit logic diagrams which succinctly describe electronic devices. These devices use solid state components sized for the design loads. Troubleshooting these systems requires new skills and equipment and fleet management must determine the level of skills necessary to maintain their electronic systems and provide adequate training for their personnel.This paper will describe the two basic types of solid state controllers, discrete logic and microprocessor, and options available to facilitate maintenance. It will discuss the fleet operator's role in improving maintainability by providing contract language that will require new diagnostic provisions. Finally, a sample evaluation test covering basic electronic knowledge and electrical theory which may help to identify areas where maintenance personnel need additional training.