This document provides information on engine control systems, including a system diagram, descriptions of onboard diagnostic systems, troubleshooting procedures, diagnostic priority charts, sensor reference values, wiring diagrams, and diagnostic trouble codes (DTCs) with descriptions and diagnostic procedures. It discusses the engine control module (ECM), sensors, actuators, and other control components. Troubleshooting guidelines are provided for intermittent issues, power supply/ground circuits, and specific DTCs related to the throttle, oxygen sensors, ignition, fuel injection, and other systems. Reference values are given for sensors that can be monitored using diagnostic tools.