Gm Mode 22 Scan Tool By Terry !!better!! Jun 2026

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For those still wanting to experiment with this historical software, here is how it worked:

Monitoring transmission fluid temperature (TFT) and pressure control solenoid (PCS) duty cycle.

I can provide the precise hexadecimal strings or setup steps for your project. Share public link gm mode 22 scan tool by terry

: 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

Often bundled with inexpensive ELM327 Bluetooth adapters, it offers functionality that used to require a $1,000+ professional scan tool. Compatibility and Usage

You can monitor automatic transmission fluid (ATF) temperature to prevent overheating. This public link is valid for 7 days

Standard OBD-II tools suffer from low "packet rates," meaning you might only get 5 to 10 data updates per second. If you are logging a drag race or diagnosing an intermittent high-RPM misfire, a delay of 100 milliseconds means missing critical data. Terry’s tool optimizes the Mode $22 data request packets, allowing users to log dozens of parameters simultaneously at refresh rates exceeding 40 to 50 Hz (updates per second). 2. Custom PID Definition Files

The tool works optimally with GM models that rely on the protocol and early GMLAN variants.

The software was developed by an individual known as "Terry" and posted in the ScanTool.net forums under the username tmk . In 2003, Terry introduced the tool to the world as a "beta form" and a personal hobby project, openly inviting the community to test it and provide feedback. The original version was a Scantool.zip file, hosted on the now-defunct Geocities platform, a fitting home for one of the internet's early community-driven projects. Can’t copy the link right now

(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 create custom dashboards to monitor specific GM-enhanced parameters in real-time.

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.

Here is a comprehensive breakdown of what GM Mode $22 is, how Terry’s tool revolutionizes data retrieval, and how you can use it to master your vehicle's diagnostics. Understanding the Basics: What is GM Mode $22?