Gm Mode 22 Scan Tool By Terry

The GM Mode 22 Scan Tool, developed by Terry (often associated with the "Scan Tool by Terry" or "STBT" project), represents a significant milestone in the world of DIY automotive diagnostics. While professional-grade scanners often cost thousands of dollars, this tool was designed to provide enthusiasts and home mechanics with deep-level access to General Motors vehicle data using affordable hardware. The Power of Mode 22

Limitations & Gotchas

Terry warns about three common traps:

Live Data Streaming: Allows users to monitor vehicle performance in real-time by reading raw data directly from the ECU.

• Fuel pump relay on/off (prime the system without cranking)
• Cooling fans (force low/high speed to test relays)
• EGR solenoid (cycle at idle to check for vacuum leaks)
• IAC (Idle Air Control) valve (extend/retract to diagnose surging)
• Injectors (balance test firing one at a time)