Gm Mode 22 Scan Tool By Terry |link| Site

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 gm mode 22 scan tool by terry

: 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 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

Here’s a structured, high-quality content outline about the GM Mode 22 Scan Tool by Terry — ideal for a blog post, video script, or forum guide (e.g., for Diesel Place or GM truck forums). GM Mode 22 Scan Tool by Terry is

3. Who Is “Terry”?

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 |

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.

The ALDL Cable: Your GM vehicle from the pre-OBDII era (1981-1995) uses a 12-pin rectangular ALDL connector (often under the steering column, sometimes marked with a small label). You need a USB-to-ALDL cable that supports the 8192 baud rate. Popular options include:

Important Warning: Do not use generic OBD-II cables with Mode 22. They lack the correct 5v logic levels and pinouts. A wrong connection can fry your ECM.

7. Practical Diagnostic Examples

Example 1 – Rough idle on Duramax

Example 2 – Poor boost / turbo lag

Example 3 – Transmission slipping

Feature Name: "Smart-Actuator Express"

Common Diagnostics Solved by Terry’s Mode 22 Tool

Problem: 1994 C4 Corvette idles rough but no OBD-II codes. Solution: Use Mode 22 to view the IAC position and TPS closed-throttle voltage. The tool reveals a TPS voltage of 0.78V (spec is 0.45-0.65V) – adjusting the TPS fixes the idle.

Problem: 1991 Camaro 5.7L TPI has hesitation under load. Solution: Log Mode 22 data during a test drive. The log shows the knock sensor pulling 8-10° of timing at 2500 RPM, but there is no audible knock. Replace the knock sensor (false triggering due to a loose torque converter bolt).

Problem: 1995 K1500 truck won’t pass emissions. Solution: Terry’s tool reads the proprietary Mode 22 O2 integrator and block learn values. Fuel trims are stuck at 160 (rich). You find a leaking fuel pressure regulator through the vacuum line—a code a generic scanner would miss.

Common Diagnoses You Can Perform

4. Real-Time Data Logging

The tool records data at up to 8-10 frames per second (depending on cable speed). You can drive the car, log the run, and then review parameters like knock retard under load, TPS drop-out, or O2 sensor cross-counts—critical for tuning or finding intermittent misfires. log the run