P28 with Hondata S300 v3 clicking main relay

[Daffy_ED9]

Was driving with my b18 turbo over last days.
Car is running on P28 with S300 without issues.
Out of sudden engine died and did not restart anymore.
Ecu fuse tripped and was replaced.
Ecu remained dead and was exchanged with a good P28.
Ecu is now up and running again, S300 is working.

Unfortunately this is only working for some seconds, then the main relay starts clicking and car won't start up anymore.
I have traced down the issue to the DC DC converter in the P28 labelled with IC12.
It is getting really really hot and then the main relay starts clicking.

I have not found any broken capacitors or signs of damage within the Ecu.
IC12 was exchanged from a known working ECU without success.

I have attached a link to a video showing the normal behavior while starting ignition and then the clicking.

https://www.youtube.com/watch?v=_vbwRw5miUs

[Spunkster]

It sounds like you have a wiring fault in the vehicle somewhere that is causing a short circuit. You should try the ECU in a known working vehicle and not plug any ECUs into your vehicle until you resolve the issue.

[Daffy_ED9]

Thanks for your response,
I missed to tell that I have another p28 here with an ostrich.
This is actually not causing the main relay / fuel pump to trigger.
So I can orettyuch nail it down to not have a wiring issue in the car.

[Spunkster]

Have the capacitors been replaced in the ECU having the issues?