Do you have any idea why my ELU is shown always on on the pfc commander screen?
No, I don't know. By "on," I guess you mean that the signal to the PCME is always low? According to the "Control System" table on factory manual page F-158, the following should be true:
With headlight switch in position I or II, OR with blower motor switch in position III or IV, OR with rear defroster switch ON, the input to PCME terminal 3B should be at a LOW state. If all those units are OFF, the signal at 3B should be a HIGH.
If you have a PFC, I have no idea how the engine should react, but at least the ELU should behave as described at its terminal N.