I have a problem with the signal from the ECU,the Igt-T to trailing coil.

I have the signal approx 2 sec after I start cranking and then it disappear,no signal at all,but if stop the engine and cranking again,I have signal for 2sec and so it disappear again.

I think it was the ECU so I tried another ECU,but the signal is still disappear.

Someone know what it can be?