Gm Mode 22 Scan Tool By Terry [2021] 📢

In the mid-2000s, the "GM Mode 22 Scan Tool by Terry" was a small but legendary piece of the early OBD-II hobbyist scene. At the time, General Motors used a proprietary diagnostic method called Mode 22, which allowed for deeper data extraction than the standard OBD-II protocols required by law.

Software: A downloadable program for a PC or laptop, requiring a compatible interface cable to connect to the vehicle.
Handheld scan tool: A dedicated device designed specifically for use with GM vehicles.

based USB interfaces. It is widely listed as part of free software bundles provided with affordable OBD-II scanners. Quadstar Tuning LLC Historical Context OBD-II free software - OBDTester gm mode 22 scan tool by terry

✅ Free or very low cost – No subscription fees
✅ Unlocks hidden GM data – Nothing else at this price point does Mode 22
✅ Lightweight – Runs on old laptops, netbooks, or even VirtualBox on a Mac
✅ Bi-directional controls – Rare in consumer tools
✅ Vast community support – Decades of forum knowledge

GM Mode 22 Scan Tool by Terry is a legacy, freeware diagnostic application designed to interface with General Motors vehicles through the OBD-II port. It is primarily recognized within automotive enthusiast communities for its ability to access manufacturer-specific data that standard generic scan tools often miss. Overview and Purpose Target Protocol : The tool focuses on In the mid-2000s, the "GM Mode 22 Scan

Code 43 (ESC – Electronic Spark Control)
Code 54 (Fuel Pump circuit low voltage)
obscure transmission codes for 4L60E and 700R4 electronic controls

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 Software : A downloadable program for a PC

The GM Mode 22 Scan Tool by Terry

What makes the "Scan Tool by Terry" notable is its focus on accessibility. In an era where automotive software is increasingly locked behind subscriptions and expensive proprietary interfaces, this project offered a way to interface with GM’s complex Electronic Control Units (ECUs) using standard laptops and inexpensive interface cables.