[Link thunder injector issue]

I have done this to fix the issue already I'm more trying to understand what causes it when the ecu is switched off  for example what is the ecu doing when I turn the ignition off to cause the injectors to start firing 

[Link thunder injector issue]

Hey guys having a bit of an issue with a r32 gtr running a link thunder ecu , basically the factory GTR r32 platform has a 12v constant feed to an injector resistor pack which then splits to each of the injectors. The issue I'm having is when I first turn the car to accessories and power up the thunder everything works sweet no issues I can connect to the ecu make changes run the engine etc. As soon as I turn the key off and disconnect power to the ecu the injectors start firing like crazy you can hear them from inside the cabin. Has anyone ran into anything similar or know where to begin? Any help is appreciated