This document is a service manual that provides information for troubleshooting and servicing generator sets and their PowerCommand 3100 controllers. It includes sections that cover control operation, circuit boards and modules, troubleshooting procedures, control service and calibration, servicing the generator, day tank fuel transfer pumps, optional enclosure fuel tank systems, and wiring diagrams. The manual contains important safety instructions and provides detailed technical information, component specifications, and repair and maintenance procedures.