Gm Mode 22 Scan Tool By Terry ❲EASY❳
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
(Enhanced Data), which is a proprietary diagnostic mode used by General Motors to provide more detailed information than the standard legislated OBD-II Mode Functionality
: It allows users to request specific Parameter IDs (PIDs) from various vehicle control modules, including the Engine Control Module (ECM) and Transmission Control Module (TCM). Accessibility
: It was developed as a free alternative to expensive professional tools like the or modern GDS2 systems. Key Technical Capabilities Enhanced PID Access
: Unlike basic scanners that only show engine RPM or coolant temperature, this tool can potentially access "hidden" data such as transmission fluid temperature, actual boost levels, and detailed sensor voltages. Compatibility
: It typically requires an ELM327-based interface (often the USB version) to connect a laptop to the vehicle's 16-pin OBD-II port. Software Ecosystem
: It is often distributed alongside other classic OBD-II software like on technical repositories such as Limitations Technical Knowledge Required
: Users must often know or manually enter specific PID addresses and headers to retrieve data, as it does not always feature an automated interface for all GM models. Legacy Status
: As a piece of older freeware, it may struggle with modern GM "Global A" or "Global B" electrical architectures found in vehicles produced after 2010, which often require newer software like Techline Connect find specific GM PIDs for use with this tool, or are you looking for modern alternatives that run on mobile devices? OBD-II free software - OBDTester gm mode 22 scan tool by terry
GM Mode 22 Scan Tool by Terry is a legacy, free software utility designed for diagnosing General Motors vehicles. It primarily serves as an interpreter for "Mode 22" (also known as Mode $22), a proprietary diagnostic mode used by GM to provide enhanced sensor data that standard OBD-II protocols do not typically reveal. Core Functionality Enhanced Data Retrieval
: Unlike generic OBD-II modes (like Mode 01), which only provide legally mandated emissions data, Mode 22 allows the user to request manufacturer-specific Parameter IDs (PIDs) Live Sensor Monitoring : It can display real-time data such as Engine RPM Coolant Temperature Vehicle Speed Fuel System Status Compatibility : The software is specifically designed to work with
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
The GM Mode 22 Scan Tool by Terry is a specialized freeware diagnostic utility designed primarily for Windows and legacy mobile platforms. It is frequently bundled as a complementary software option for ELM327-based Bluetooth and USB scan tools. Key Features and Capabilities
While modern professional scanners like the FOXWELL NT510 Elite offer comprehensive bi-directional controls, this tool serves as a lightweight alternative for specific GM diagnostics:
Platform Support: The software is compatible with Windows, OSX, and older mobile operating systems such as PalmOS and Pocket PC.
Enhanced Mode 22 Access: It is designed to utilize the "Mode 22" diagnostic request, a proprietary GM protocol used to retrieve specific data parameters (PIDs) that standard generic OBD-II Mode 01 requests may not cover.
Core Diagnostic Functions: Like most ELM327-compatible software, it allows users to: Read and clear diagnostic trouble codes (DTCs). Monitor real-time engine data and sensor values. Detect specific system pressures and status indicators. GM Mode 22 Scan Tool by Terry is
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.
"GM Mode 22 Scan Tool by Terry" is legacy freeware commonly bundled with ELM327 OBD-II interfaces for reading enhanced GM-specific diagnostics. Designed for older operating systems, it provides access to specialized vehicle data parameters not available in standard generic OBD-II modes. For modern GM vehicles, users typically transition to factory-level tools like the OEMTools GM MDI or advanced third-party scanners. Interfuse LLC. Obd2 elm327 v1.5 usb can bus scanner | PDF - Slideshare
The GM Mode 22 Scan Tool by Terry is a specialized, often free software utility designed for deep-level diagnostics on General Motors vehicles, typically used in conjunction with low-cost ELM327 OBD2 interfaces. Overview of the Tool
Unlike generic OBD2 scanners that only read "Mode 01" global data, this tool targets Mode 22, a manufacturer-specific diagnostic mode used by GM to provide access to enhanced data parameters (PIDs) not available through standard protocols.
Platform Compatibility: It is frequently bundled with ELM327 USB or Bluetooth diagnostic kits as part of a free software suite.
Target Audience: It is primarily aimed at DIY enthusiasts and older GM vehicle owners who
Key Capability: It enables users to view proprietary sensor data that generic tools might miss, such as specific transmission temperatures, ABS data, or body control module (BCM) status. Functionality Comparison
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 Common Mode 22 PIDs You’ll Actually Use Unlike
Common Mode 22 PIDs You’ll Actually Use
Unlike Mode 01, Mode 22 uses two-byte hexadecimal PIDs. Here are Terry’s “most-saved-my-butt” PIDs for a typical V8 truck (P01/P59 PCM):
| PID Hex | Description | Why It Matters |
| --- | --- | --- |
| 0x1654 | Transmission Turbine Shaft Speed | Detects TCC slip or internal clutch failure |
| 0x1655 | Transmission Output Shaft Speed | Calculate true gear ratio |
| 0x1668 | Line Pressure (PSI) | Low pressure = worn pump or cross leaks |
| 0x16B0 | Knock Retard (degrees) | False knock from loose converters vs real detonation |
| 0x16C1 | Left & Right Fuel Trim Cell | Long-term cell correction (not seen in Mode 01) |
| 0x16D3 | EGR Position Sensor (actual vs commanded) | Sticky EGR valves |
10. Where to Download & Get Help
- Download: Search “Terry’s Mode 22 Scan Tool” on Diesel Place forums (look for pinned threads by “thefermanator” or “Terry”).
- Support: Forum threads often contain custom PID files and troubleshooting.
- Alternatives: For newer GM vehicles, consider Mode 23 Tool or GMLAN Scanner.
5. Compatibility
Designed specifically for 8192-baud ALDL GM vehicles, typically:
- 1986–1995 GM Cars & Trucks (Chevrolet, GMC, Pontiac, Oldsmobile, Buick, Cadillac)
- Engines: 2.8L, 3.1L, 3.4L, 5.0L, 5.7L (TBI and early MPFI), 4.3L V6, 6.2L/6.5L Diesel (mechanical pump with electronic controls)
- Control Modules: ‘7165,’ ‘730,’ ‘7747,’ ‘7427’ ECMs, among others.
Step-by-Step: Diagnosing a Torque Converter Clutch (TCC) Issue with Mode 22
Terry’s classic case: “Customer says RPM jumps 200-300 RPM on the highway. No codes.”
Step 1 – Connect & Enter Enhanced Mode
On your scanner, select “GM Enhanced” or “Manufacturer Specific.” Choose the PCM (engine/transmission module).
Step 2 – Select Mode 22 PIDs
Do not use “All Data.” Hand-pick:
- Engine RPM (Mode 01 or 22 – either works)
- TCC Slip (Mode 22 PID
0x1656on most LS1-based PCMs) - Transmission Input Shaft Speed
- Transmission Output Shaft Speed
Step 3 – Road Test with Graphing
Drive at steady 50-55 mph in 4th gear. Command TCC lockup via scanner (bi-directional function). Watch the TCC Slip PID.
- 0-20 RPM slip – Healthy
- 50-150 RPM slip – Worn TCC clutch
- Over 200 RPM slip – TCC regulator valve or PWM solenoid issue (common in 4L60E)
Step 4 – Verify with Gear Ratio
Using Input Shaft RPM / Output Shaft RPM:
- 4th gear locked should be ~0.70:1 ratio. If it’s ~0.75:1 but slip PID says 0, you have a failed sensor or wrong PID definition.
“That’s the power of Mode 22,” says Terry. “Generic data would show RPM and VSS, but you’d never see the slip. You’d replace the torque converter unnecessarily.”