Tech 2 scanners reboot when the engine cranks due to a temporary drop in voltage. The internal power supply in these clones is not as robust as the original units and can’t handle the voltage dip, causing the device to restart.
Common Fixes (and Their Drawbacks)
- Internal power supply mods: Invasive and require soldering—risky for inexperienced users.
- External power via inline cable: Doesn’t fully solve the issue because the Tech 2 still defaults to OBD2 pin 16 for power during ignition.
The Best Fix: A Switched OBD2 Extension Cable The most effective workaround is using an OBD2 extension cable with a power switch that disables pin 16 (OBD2 power). This forces the Tech 2 to use an external power source instead.
What You’ll Need:
- Switched OBD2 extension cable
- External 12V power source (wall adapter or independent 12V battery, not the vehicle’s battery)
Steps:
- Connect the Tech 2 to your car using the switched extension cable.
- Use the switch to disable pin 16 (OBD2 power).
- Plug the external 12V power into the inline connector of the Tech 2.
This setup ensures the scanner stays powered during engine cranking and avoids rebooting.
Fixing the “I-Bus Missing” Error (Saab 9-3 and Similar Models) In some vehicles like the Saab 9-3, you may see an “I-Bus Missing” message. This occurs because standard OBD2 extension cables don’t include all necessary pins (e.g., Pin 1).
Solution:
- Identify which OBD2 pins your vehicle uses (e.g., Saab 9-3 Mk2 uses Pins 1, 4, 5, 6, 7, 14, 16).
- Modify the extension cable by adding jumper wires to connect missing pins.
- Secure and insulate the modification properly for durability.