An integrated diagnostic system includes interface connectors to connect to a plurality of instruments/instrument modules, including engine analyzers, gas analyzers, oscilloscopes, scanners, network connections, and/or other desired peripheral modules. These modules advantageously interface to the system through diverse parts, connections and with various protocols. The system may connect to a network, wired or wireless, for interfacing among processors and modules, and with an internet connection for interaction with remote resources including databases and expert systems.