Gm Mode 22 Scan Tool By Terry //free\\
The GM Mode 22 Scan Tool by Terry is a legacy, free software utility designed to access manufacturer-specific diagnostic data (Mode 22h PIDs) on older General Motors vehicles. It operates with ELM-based OBD-II interfaces to monitor ECU and TCM parameters, though it lacks support for modern CAN FD protocols and is strictly limited to data retrieval. For a list of free OBD-II software options, including this tool, see Interfuse LLC. OBD-II free software - OBDTester
Hardware Requirements: Getting Connected
To use the GM Mode 22 Scan Tool by Terry, you need proper hardware. The tool is software; the interface is what matters.
What Exactly is Mode 22?
In standard OBD-II (SAE J1979), Mode 01 requests generic live data (RPM, coolant temp, speed). Mode 22 is a GM-specific proprietary mode (often called “High-Speed Data” or “Enhanced Parameters”). gm mode 22 scan tool by terry
If you are a vintage GM enthusiast, a professional mechanic working on LT1/LT4 engines, or a DIYer trying to resurrect a C4 Corvette, a 3rd-gen Camaro, or a square-body truck, understanding this tool is not just helpful—it is essential. This article dives deep into what Mode 22 is, why Terry’s tool became an industry legend, and how it can save you hours of diagnostic headaches.
Where to Find It Today
Since Terry’s original software was distributed via BBS (bulletin board systems) and early websites in the 1990s, it lives on through the GM tuning community. You can often find the executable and required cable schematics on: The GM Mode 22 Scan Tool by Terry
Portability: Due to its small file size (approx. 1.49Mb), it is easy to install and deploy on older hardware. Limitations ELM327 Software - Interfuse LLC.
- DIY GM owners who want deeper diagnostics than basic OBD2 readers provide.
- Independent mechanics needing a low-cost, GM-focused troubleshooting tool.
- Not ideal as a primary shop tool for heavy-duty diagnostics, programming, or bi-directional service work.
| Tool | Protocol | Price | Best For | |------|----------|-------|-----------| | GM Mode 22 by Terry (legacy) | ALDL Mode 22 | Free | Budget, simple diagnostics | | Scan9495 | ALDL Mode 22 | $30 shareware | LT1/LT4 specific (94-95) | | TunerPro RT | ALDL + OBD-II | Free (donation) | Advanced tuning & logging | | ALDLLogger | ALDL Mode 22 | Free | Mac/Linux users | | Tech 1 w/ GM cartridge | All GM modes | $500+ used | Professional restoration | DIY GM owners who want deeper diagnostics than
Furthermore, the tool is a staple for those performing engine swaps. When putting a modern GM drivetrain into an older chassis, communication between the various control modules can be tricky. Terry’s tool helps verify that the PCM is receiving the correct signals from the rest of the vehicle, making it an indispensable part of the "LS swap" toolkit.
