While "Terry's" tool is a lightweight utility, it sits between basic code readers and professional factory equipment: OBD II Generic PID Diagnosis - MOTOR Information Systems
GM Mode 22, also known as "Mode 22," is a feature in some General Motors (GM) vehicles that allows for advanced scan tool functionality. It's a protocol that enables communication between a scan tool and the vehicle's onboard computer, providing detailed information about the vehicle's systems and allowing for advanced troubleshooting and repair. gm mode 22 scan tool by terry
Early versions were DOS or early Windows based, but more refined versions (often packaged as "TTS DataMaster" or similar, with Terry’s foundational logic) include the ability to to a file and play it back. This allows you to drive the car, record a stumble or misfire, and then review the data frame-by-frame later. While "Terry's" tool is a lightweight utility, it