2002 civic, key sign flashing, not starting, micu problem

[nemena]

Hello guys,

I have a 2002 3 door 1.4 Civic, key sign flashing, car doesn't start.
In immo I have dtc: "No communication between imoes unit and immobilizer unit". Imoes unit in this car is the micu.
I have checked wiring from immo to micu and from micu to engine control unit. All good, checked signal with oscilloscope, nice, undisturbed signal.
I tried to make a replace a MPCS/MICU/IMOES with diag tool to match them together, but doesn't let me, it shows a message "immobilizer is not normal". Keys are recognized.
Can the micu be the problem? I can't think of anything else.
Is it a plug and play if I buy a used one? I read it is, but if it is a plug and play why is there a function in hds "Replace MPCS/MICU/IMOES"?
Thank you in advance
Peter

[GameTheoryOptimal]

take a look at that document. it gives you the procedure to figure out what is ''not normal'' right now.
hope it helps!

[nemena]

Thank you. But I have D-2, but I don't know how, since it is an immo 3 system, which does not include the imoes unit.
Do you have wiring diagram by any chance?

[yapm]

sometime only you have to change the main relay i did on honda accord with the same problem and works

[nemena]

Thanks to everyone, it was the fusebox (micu) that had to be replaced and had to be registered to the immo with hds.