Open Terry's software on your laptop or device. Select the correct COM port or Bluetooth connection matching your adapter. Set the baud rate (usually 9600 or 38400 for older VPW vehicles). Step 3: Loading the PID Database
Generic tools show short-term (STFT) and long-term fuel trims (LTFT). Terry's Mode 22 tool allows users to see fuel trim cell data. GM vehicles organize fuel management into distinct "cells" based on RPM and engine load. Pinpointing which specific cell is lean or rich makes tracking down vacuum leaks or failing injectors much faster. 2. Transmission Metrics
The remains a testament to the power of the automotive enthusiast community. By bypassing proprietary corporate barriers, it gives everyday mechanics access to the deep digital heartbeat of General Motors vehicles. Whether you are hunting down a frustratingly elusive misfire, logging data for a custom street tune, or diagnosing an ABS fault, this community tool offers commercial-grade power without the commercial price tag.
This usually indicates a timing mismatch. Ensure your adapter supports the GM J1850 VPW protocol. You may need to adjust the latency timer settings in your PC's Device Manager down to 1ms. gm mode 22 scan tool by terry
: Plug your ELM327 tool into the computer via USB or pair it via Bluetooth. Ensure the corresponding Virtual COM Port drivers (often FTDI or Silicon Labs drivers) are fully updated in your Windows Device Manager.
Unlike rigid handheld scanners, Terry’s tool allows users to import or edit custom PID maps. If you are running a niche configuration—such as a turbocharged 5.3L LS swap with an aftermarket 3-bar MAP sensor—you can program the exact hexadecimal memory addresses into the tool to read boost pressures accurately. 3. RAM Address Interrogation
To appreciate Terry's scan tool, you must first understand the architecture of onboard diagnostics (OBD). Open Terry's software on your laptop or device
Observe raw switching speeds and voltage sweeps to diagnose lazy sensors.
, often referred to as "Request Enhanced Emission Related Data" or simply "PID Request," is a custom mode that allows diagnostic tools to communicate directly with the vehicle's ECU to retrieve specific, non-standardized data parameters (PIDs).
What (like an OBDLink or ELM327) do you plan to use? Step 3: Loading the PID Database Generic tools
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.
Standalone DIY microcontroller builds equipped with a CAN-bus shield. Key Capabilities and Diagnostic Functions
If you’ve spent any time under the hood of a late-90s to mid-2000s General Motors vehicle, you’ve likely run into the limitations of generic OBD-II scanners. They’ll give you a check engine light code, but they won’t tell you why a 4L60E transmission is slipping or why the ABS light triggers on a bumpy road.
Mode 22 is primarily found on GM vehicles from ~1996 to 2006 (pre-CAN bus transition), covering:
Terry’s classic case: “Customer says RPM jumps 200-300 RPM on the highway. No codes.”