Communicates directly with GM ECMs/PCMs to retrieve enhanced parameters.
“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.”
Unlike modern generic scan tools that use a standard J1850 or CAN bus, Terry’s tool sends a specific to the ECM. The ECM responds by dumping a packet of 32–64 bytes of raw RAM data. Terry’s software then decodes that raw hex data into human-readable values.
Designed specifically for GM vehicles, typically:
Here's where Mode 22 comes in. It is an , part of the proprietary SAE J2190 standard, used specifically by Ford and General Motors. While standard OBD2 PIDs (Mode 01) can tell you the engine RPM or coolant temperature, Mode 22 allows a scan tool to reach deeper into the vehicle's computer:
Load the specific PID configuration file (.csv or .txt) matching your vehicle's engine architecture (e.g., LS1 V8, 3800 V6, or Duramax Diesel). This populates the software with human-readable labels instead of raw hex codes. Step 4: Live Data Interrogation
A special cable that converts the 12-pin ALDL connector (usually found under the dashboard) to a serial port connector (RS-232). Connection Guide:
In the world of GM tuning and diagnostics, “Terry” is a whispered name of respect. While multiple developers have created Mode 22 interfaces, the version most widely known as “the Terry tool” or “Terry’s Mode 22 Scanner” originated from the early 2000s GM EFI tuning forums (like thirdgen.org, DIY-EFI, and Gearhead-EFI).
The is more than just an old software program; it's a piece of digital history. It embodies the hacker spirit of the early internet, where individuals shared their creations for the benefit of an entire community, free of charge. While its time has passed and it has been superseded by more modern and polished applications like Torque Pro and OBDLink, its legacy lives on. It democratized access to complex GM data and served as a foundational building block for the DIY diagnostic community we have today. For a Windows XP-era enthusiast with a GM vehicle and a soldering iron, this little program was the ultimate tool for peering under the hood of their car's digital brain.
The GM Mode 22 scan tool is recommended for:
Open Terry's software. Go to settings and select the correct COM port assigned to your adapter. Set the baud rate (typically 115200 or 38400).
Communicates directly with GM ECMs/PCMs to retrieve enhanced parameters.
“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.”
Unlike modern generic scan tools that use a standard J1850 or CAN bus, Terry’s tool sends a specific to the ECM. The ECM responds by dumping a packet of 32–64 bytes of raw RAM data. Terry’s software then decodes that raw hex data into human-readable values. gm mode 22 scan tool by terry
Designed specifically for GM vehicles, typically:
Here's where Mode 22 comes in. It is an , part of the proprietary SAE J2190 standard, used specifically by Ford and General Motors. While standard OBD2 PIDs (Mode 01) can tell you the engine RPM or coolant temperature, Mode 22 allows a scan tool to reach deeper into the vehicle's computer: Communicates directly with GM ECMs/PCMs to retrieve enhanced
Load the specific PID configuration file (.csv or .txt) matching your vehicle's engine architecture (e.g., LS1 V8, 3800 V6, or Duramax Diesel). This populates the software with human-readable labels instead of raw hex codes. Step 4: Live Data Interrogation
A special cable that converts the 12-pin ALDL connector (usually found under the dashboard) to a serial port connector (RS-232). Connection Guide: You’d replace the torque converter unnecessarily
In the world of GM tuning and diagnostics, “Terry” is a whispered name of respect. While multiple developers have created Mode 22 interfaces, the version most widely known as “the Terry tool” or “Terry’s Mode 22 Scanner” originated from the early 2000s GM EFI tuning forums (like thirdgen.org, DIY-EFI, and Gearhead-EFI).
The is more than just an old software program; it's a piece of digital history. It embodies the hacker spirit of the early internet, where individuals shared their creations for the benefit of an entire community, free of charge. While its time has passed and it has been superseded by more modern and polished applications like Torque Pro and OBDLink, its legacy lives on. It democratized access to complex GM data and served as a foundational building block for the DIY diagnostic community we have today. For a Windows XP-era enthusiast with a GM vehicle and a soldering iron, this little program was the ultimate tool for peering under the hood of their car's digital brain.
The GM Mode 22 scan tool is recommended for:
Open Terry's software. Go to settings and select the correct COM port assigned to your adapter. Set the baud rate (typically 115200 or 38400).