Look at Godiag GT100 OBD2 Break Out Box, there are 2 buttons 12V (30) and 12V(15), what are they used for?
godiagshop.com engineer replied:
12V (30): Used as a battery power switch for ecu
12V(15): Used as ECU ignition switch
Sometimes when reading ECU data, it will prompt to turn on or off the ignition switch.
Okay, maybe Godiag GT100 OBD2 Break Out Box manual will help.
Hope it helps!