Silly question perhaps, when the ECU is immo locked / engine not allowed to start, how is this put into effect on ME-s? Fuel pump relay shut down, injector / coil outputs disabled, some internal latch, or what?

Reason for the question: I am currently penetrating some immo related things (with poor results so far) and I also finally got my rpm signal stimulation to work with the ECU on the bench (long fight with silly obstacles, used to work before on other ECUs), and I got the ECU to show me RPM, along with meaningful injection time and ignition advance figures shown through diagnostics. Yet, since I am unsure about my ECU with respect to immo state at this particular moment, I'd need a sure way to verify if the ECU is "running the engine" or not. It is bare in terms of stuff attached to it, and lots of connections to check, so I though I'd ask to have a head start. (Eventually I plan to build a complete stimulation board for it, but cannot find time).