The is more than a cable. It is a philosophy: that the manufacturer’s proprietary data belongs to the owner of the car. By building or buying a Mode 22 scanner, you are keeping the OBD1 era alive, fixing your own vehicle, and tuning with precision that dealerships in the 1990s couldn’t even offer.
You have two paths: build the original DIY version or buy a modern equivalent. Here is the classic DIY method that made Terry famous. gm mode 22 scan tool by terry
If you’ve ever felt like a standard OBD-II scanner was only giving you half the story of your General Motors vehicle, you’re not alone. While generic scanners focus on standard codes, enthusiasts and DIY mechanics often turn to specialized freeware like GM Mode 22 Scan Tool by Terry to dig deeper. What is GM Mode 22? The is more than a cable
Garbage characters on screen. Fix: You have a baud rate mismatch. Mode 22 requires exactly 8192 baud, 8 data bits, 1 stop bit, no parity. You have two paths: build the original DIY
The knock sensor on LT1, L98, and TPI engines is notoriously sensitive. Mode 22 allows you to see knock retard counts live. You can hear pinging, but Terry’s tool shows you exactly when the ECM pulls timing, down to 0.1-degree increments.